End to End Security with z Systems

End to End Security with z Systems
Front cover
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End to End Security
with z Systems
Understand z Systems end-to-end
Secure z Systems for z/OS, z/VM
and Linux for z Systems
Understand security from a
use case perspective
Lydia Parziale
Douglas Cardosa
Willian Rampazzo
Ian Broadbent
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International Technical Support Organization
End to End Security with System z
March 2015
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Note: Before using this information and the product it supports, read the information in “Notices” on page v.
First Edition (March 2015)
This document was created or updated on March 12, 2015.
© Copyright International Business Machines Corporation 2014. All rights reserved.
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Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v
Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Chapter 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Systems of Record and Engagement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.1 Systems of Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.2 Systems of Engagement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 The security perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.1 Information security principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.2 Security and z Systems features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.3 Putting it all together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2. Security Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Securing the onion, defense in depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.1 The onion peel, protecting the physical IT infrastructure . . . . . . . . . . . . . . . . . . . 11
2.1.2 Right after the onion peel, protecting the servers . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.3 To the frying pan, when data physically leaves the data center . . . . . . . . . . . . . . 12
2.2 Inside the bits protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.1 Operating System Security - The Hypervisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.2 Operating System Security - The Guest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.3 Application security, protecting the database server. . . . . . . . . . . . . . . . . . . . . . . 14
2.2.4 Application security, protecting the application server . . . . . . . . . . . . . . . . . . . . . 15
2.2.5 Communication security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Chapter 3. Use case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Use case description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.1 General architecture and transaction flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.2 Mobile device management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.3 Securing the network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Securing the enterprise applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 Operating system security - z/VM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.1 Virtual machine security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.2 Hypervisor security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Data security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5 Operating system security - Linux on IBM z Systems . . . . . . . . . . . . . . . . . . . . . . . . . .
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End to End Security with z Systems
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End to End Security with System z
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This IBM® Redpaper™ provides a broad understanding of the components necessary to
secure your IBM z Systems environment. Here, we provide an end-to-end architectural
reference document for a use case that employs both mobile and analytics. This IBM
Redpaper will be an end to end walk through of security on z Systems from the systems of
record through the systems of engagement. We will discuss security in terms of transactions what happens once a transaction hits the system of engagement and what needs to be in
place from that moment forward.
The audience for this IBM Redpaper is IT architects and those planning to use z Systems for
their mobile and analytics environments.
This paper was produced by a team of specialists from around the world working at the
International Technical Support Organization, Poughkeepsie Center.
Lydia Parziale is a Project Leader for the ITSO team in Poughkeepsie, New York, with
domestic and international experience in technology management including software
development, project leadership, and strategic planning. Her areas of expertise include
business development and database management technologies. Lydia is a certified PMP and
an IBM Certified IT Specialist with an MBA in Technology Management and has been
employed by IBM for over 25 years in various technology areas.
Willian Rampazzo is a Software Engineer at Linux Technology Center (LTC) in IBM and an
Assistant Professor for a Computer Science Bachelor course in Brazil. He has a Bachelor in
Computer Science and an MBA in Information Technology Security Management. He has
being working with z Systems for 12 years, all at IBM, and has worked as a z/VM® system
programmer and as a Linux on z Systems administrator for IBM Internal Account and now is
focused on development for Linux on z Systems at LTC
Special thanks to Nigel Williams from the IBM Client Center, Montpellier, France for assisting
in creating the use case discussed in this IBM Redbooks® publication.
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End to End Security with z Systems
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Chapter 1.
This chapter will describe the following:
򐂰 Systems of Record
򐂰 Systems of Engagement
We also explain the importance of end to end security on z Systems as it relates to both the
systems of record and the systems of engagement. Also discussed is the difference between
security and integrity and the importance of each.
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1.1 Systems of Record and Engagement
In this section, we describe the unique qualities of the systems of record and systems of
1.1.1 Systems of Record
The Systems of Record are largely geared towards passively providing information to a
company's workers. "Systems of Record" are the enterprise resource planning (ERP)-type
systems we rely on to run our businesses today (financials, order processing, customer
relationship management, human resources, etc). They have to be " correct" and "integrated"
so all data is consistent. And they were traditionally designed for people who have no choice
but to use them. They passively provide information to the enterprise and its business
partners, often through a firewall.
A large percentage of the data and transactions, as well as massive data warehouses for
business analytics, originates or resides on IBM z Systems.
Systems of Record on z Systems are mainly on-premises, core transactions based in z
Systems that benefit from the security that is designed into z Systems.
1.1.2 Systems of Engagement
Geoffrey Moore, speaker, advisor and author of many business evolution related books
introduced the concept of Systems of Engagement as the Future of IT and the transition in IT
investment focus from Systems of Record to Systems of Engagement.
Systems of Engagement revolves around the transition from current enterprise systems
designed around discrete pieces of information (the records) to systems that are more
decentralized, incorporate technologies which encourage peer interactions (such as
Facebook and Twitter) and often leverage cloud technologies to provide the capabilities to
enable those interactions (such as mobile applications). These systems often must provide
24x7 indicators of the health of a business (analytics) as well.
1.2 The security perspective
Systems of Engagement is an evolution of IT into a more collaborative based environment,
and hence, security technologies must evolve as well. When moving from Systems of Record
to Systems of Engagement, the concern becomes about not only giving employees and
partners access to the enterprise network without compromising it, but also controlling and
managing consumer access to data. Of course there are firewalls for the consumers, but now
companies also want to create personalized, rich media experiences at the edge, through
real-time processing. All this creates a new raft of architecture challenges.
In this section, we introduce this IBM Redpaper’s prime topic - that of the end-to-end security
challenges from a z Systems perspective in the context of information security principles.
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1.2.1 Information security principles
Regardless of the form that data may take, information security is the practice of protecting
and defending information from unauthorized access and use, disclosure, disruption or
modification. All of these form the triad of basic information security:
The set of rules or a promise that limits access or places restrictions
on information. It is basically equivalent to privacy. Confidentiality
involves protecting data from unauthorized access or disclosure.
The assurance that the data being accessed or read has neither been
tampered with nor been altered or damaged since the last authorized
access. Integrity involves maintaining and assuring the accuracy and
consistency of data through its life-cycle.
Information is available when it is needed. Availability is synonymous
with uptime when discussing hardware. When considered in the larger
picture, uptime is not just a function of hardware, but also of software
stability and resilience to disaster or attack. Availability is about
resilience, business continuity, and disaster recovery. You must ensure
backup information and systems are in place for recovery purposes
These three elements of the triad are considered to be the most crucial components of
security. The purpose of information security is to preserve these three elements.
1.2.2 Security and z Systems features
In this section, we provide a high level overview of the z Systems features and benefits and
how the various operating systems and applications are able to exploit the built-in z Systems
security features.
The IBM z13 as a IBM’s newest addition to the mainframe has a rich and proven legacy of
delivering a secure infrastructure. It’s built on a set of hardware secuirty capabilities that
include multi-state operation modes, storage key isolation, high speed standards-based
encryption, logical partitions as well as many other features and benefits. Some of these
features and benefits that enhance the security of the IBM z13 include:
򐂰 Cryptographic cards
Crypto Express5S is an accelerator feature capable of intelligent encryption of sensitive
data executed faster than previous generation Crypto Express4S, with less disk
requirement and centralized key management
򐂰 CP Assist for Cryptographic Functions (CPACF)
Cryptographic processor unit available on every core, enabled as a no charge feature
򐂰 EAL5+ (Common Criteria Evaluation Assistance Level 5+) certified, a regulatory
certification for logical partitions (LPARs) verifying separation of partitions to improve
򐂰 EEC (Elliptic Curve Cryptography)
Cryptographic capabilities designed to provide public key support for constrained digital
򐂰 TKE (Trusted Key Entry)
A feature that is a means for ensuring secure creation and management of key material
and for managing the crypto adapters on the host
Chapter 1. Introduction
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Operating system
IBM z Systems servers support multiple operating systems. In this section, we provide an
overview of the security features available for the operating systems z/OS®, z/VM and Linux
on z Systems
The security of z/OS is centralized on the System Authorization Facility, which can provide its
own security services, but is more likely to route requests for security services to another
security manager such as the Resource Access Control Facillity (RACF®) .
Building on the hardware foundation, the z/OS operating system provides software security
capabilities such as RACF, and the Integrated Cryptographic Service Facility (ISCF).
Technologies such as Secure Sockets Layer (SSL), Kerberos V5, Public Key Infrastructure,
multilevel security and exploitation of IBM mainframe cryptographic features are all available
in z/OS.
Additional features and benefits include:
򐂰 RACF and IBM Distributed Identity Data(IDID)provides discrete, end to end authentication,
transaction auditing, and identity mapping
򐂰 Cryptography options supporting advanced encryption processing
򐂰 PKI services centrally manage certificates
򐂰 High level security connection to backend applications via hipersockets
IBM z/VM is the z Systems virtualization platform and supports more virtual servers than any
other in a single footprint. z/VM provides isolation and protection of virtual machines from
each other, and between virtual machines and the system overall. These functions are
provided by the z/VM Control Program (CP) and supported by features of the z/Architecture®
and z Systems hardware. While the core capability of security and integrity is provided by CP,
without an external security manager(ESM) such as RACF, the management of this capability
is quite basic.
Some of the features and benefits that z/VM provides in support of a more secure
environment include:
򐂰 The z/VM hypervisor
The z/VM hypervisor, which refers to a system that virtualizes the real hardware
environment, is designed to help extend the business value of mainframe technology while
providing availability, security and operational ease. The hypervisor, also called a virtual
machine manager, is a program that allows multiple operating systems to share a single
hardware host. Each operating system appears to have the host's processor, memory,
and other resources all to itself. However, the hypervisor is actually controlling the host
processor and resources, allocating what is needed to each operating system in turn and
making sure that the guest operating systems (called virtual machines) cannot disrupt
each other.
򐂰 Cryptography options supporting advanced encryption processing
– Supports Crypto Express5S feature
– Can be configured as coprocessors for secure key transactions
– Can be configured as accelerators for Secure Sockets Layer(SSL) communications
Linux on z Systems
In addition to the security provided by the z/VM operating system, Linux on z Systems guests
are also provided with a Pluggable Authentication Module (PAM) LDAP function to improve
security and to reduce administrative tasks. With the PAM function, you can avoid defining
End to End Security with z Systems
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users under a z Systems Linux in every Linux server and can have a unique user ID and
password on z/VM, z/OS, and Linux.
For more information regarding security for Linux on z Systems, see Security for Linux on
System z, SG24-7728
z Systems is the only commercial operating system that has achieved EAL 5+ certification.
This certification means that although different workloads are running on the same hardware,
they are protected when running in separate partitions; one logical partition (LPAR) cannot
reach across boundaries into the next LPAR and compromise its security. The LPARs are
allocated their own resources and are secure and separate environments.
Additionally, the Central Processor Assist for Cryptographic Function (CPACF) has been
redesigned to allow for the handling of higher volumes of transactions. Many applications that
exploit the CPACF benefit such as:
IBM InfoSphere® Guardium® Data Encryption for DB2® and IMS™ Databases
DB2 built in encryption
z/OS Communication Server: IPsec/IKE/AT-TLS
z/OS System SSL
z/OS Network Authentication Service (Kerberos)
IBM Encryption Facility for z/OS DFSMSdss encryption feature
IBM Encryption Facility for z/OS
z/OS Java SDK
Linux on System z®; kernel, openssl, openCryptoki, GSKIT
The IBM DS8000® disk storage series offers a self-encrypting disk that uses IBM Full Disk
Encryption (FDE) disks and flexible key manager software. The DS8000 encryption secures
data at rest and offers a simple, cost-effective solution for securely erasing any disk drive that
is being retired or repurposed (cryptographic erasure).
For more information about how even the z13 storage is secured, see IBM DS8870 Disk
Encryption, REDP-4500.
Securing the communication is important to keep the integrity of a request and the integrity of
the data going through the communication. Some ways that the IBM z Systems secure
communications include:
򐂰 CPACF provides communication encryption (to applications such as the IBM HTTP
򐂰 At the operating system level, the hypervisor provides solation and integrity of virtual
servers in such a way that bad behavior by one cannot compromise the execution or data
associated with another.
1.2.3 Putting it all together
IBM z Systems, with its enhanced security, brings your systems of record together into your
systems of engagement in a secure environment that can support the volume of transactions
that mainframe users are accustomed to.
As an example, in today’s mobile era, over 10 billion devices are accessing information.
Enterprises are challenged with integrating new mobile services with existing organizational
Chapter 1. Introduction
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processes, without sacrificing the client’s experience. Approximately 70% of all enterprise
transactions involve IBM z Systems. The new IBM z13 with its enhanced data processing
capabilities can play an important role by providing the secure and stable base that you need
to extend your existing enterprise data and transactions to mobile users. Figure 1-1 shows
how, in a typical environment, access to applications and interaction with the systems is
achieved from mobile devices.
Figure 1-1 From systems of record to systems of engagement to your mobile devices
The IBM z13 maintains levels of securty at each step of the way, from systems of record to
systems of engagement to the mobile devices.
End to End Security with z Systems
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Chapter 2.
Security Overview
The world is becoming more digitized and interconnected, which open the door to emerging
threats, leaks and attacks. The average cost of a security breach is $5.8 million US dollars
(USD)! Analytics, mobile, social, and cloud computing all have one thing in common: They
need a platform that has a deeply integrated security stack, as shown in Figure 2-1.
Figure 2-1 Analytics, mobile, social, and cloud computing require a deeply integrated security stack
When talking about security, a consideration that needs to be made is that it must be applied
to the environment as a whole, and not to a single machine, operating system or application.
© Copyright IBM Corp. 2014. All rights reserved.
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In general, security must be applied to the physical location of an organization, on laptops or
desktops employees use to perform their daily work. It must be applied on data centers,
servers, and network. Think about security as an onion, where layers involving the core can
be considered as levels that needs to be reached combined with the security access.
As an example, if access is needed to reach the core, it is analogous to a console from a
server in a data center with an administrator user ID on it, access to all levels must be
granted, from physical to logical.
In this chapter we provide an overview of this kind of layered security, used by most
companies, known as defense in depth.
End to End Security with z Systems
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2.1 Securing the onion, defense in depth
The first steps to make an organization less exposed to the threats and vulnerabilities of a
business environment are to identify and employ the most adequate security requirements for
the business and, based on that, create the policies that will guide the overall configuration of
the IT infrastructure.
To grant access to different layers of a defence in depth model, a well established information
security policy must be in place defining the roles and the rules for controlling access to data.
For the vast majority of companies, the most valuable asset is the information and to secure
it, the first step is to create an information security policy. The basic purpose of an information
security policy is to protect the information. A constant challenge is to make information
always available and at the same time always secure.
The start point is setting rules for users based on their expected behavior, as an example,
system administrators will have different privileges than management or security personnel.
As a default, roles must always be defined with the least access needed. This definition helps
to keep a strict control of who is accessing the data.
A complete information security policy will also cover the physical security of desktops,
laptops, servers and data centers.
When an information security policy is in place, there exists the role of security personnel or
team and this role must have access to monitor, probe, and investigate any suspect activity
on a system, network or data center. The security role must also be explained, in detail, in the
information security policy as well as the consequences for any violation.
An information security policy will not ensure total security alone. It will be a framework
containing preferred practices, rules, and roles that the employees will follow. It will help
minimize the risk of a violation and also will help tracking compliance with regulations and
To make the information security policy valid, all employees in an organization must have
access to it, must read and understand it and usually will sign, or electronically sign it,
agreeing that they have read it. This turns staff into participants in the effort to secure
information assets.
2.1.1 The onion peel, protecting the physical IT infrastructure
Following the analogy of the onion, the first layer of an IT infrastructure that must be protected
is the physical access to the data center. Typically, only maintenance people, like hardware
support personnel, network support personnel, facility support personnel, and a restricted
number of system administrators need to have access to data centers, but that is a decision
that should be made while developing the information security policy for the organization.
The roles of those who have access to a data center may vary from organization to
organization and there are cases where access to the data center is not part of the role of
some people, but they will occasionally need to access the data center. This is also
acceptable, must be stated at the information security policy, and must be controlled for audit
purpose. Access from people that do not maintain the data center may cause unnecessary
problems such as mistakenly turning a server turn off or unplugging a network cable.
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There are some solutions that can be used to control the physical access of a data center. It
will mainly depend on how the organization wants to protect the data center and how much
the organization is willing to spend securing the data center.
Choosing what kind of security access will be in place in the data center is an important
decision considering information is one of the most valuable assets of an organization. Some
options to accomplish data center security access are using locks, biometrics, guards,
identification badges, or any other way that prevents unauthorized access from people and
grant access just to permitted people, considering the least access need.
As an example, in an organization that has a data center accessed by a few people, a lock will
typically be enough. In a data center that does not have a card reader mechanism, a guard
can verify employees identification badges. More than one method to grant access can also
be used to make the data center security stronger, so as an example, a guard can verify
employees identification badges and make sure they are the real owners of it and a card
reader can grant or deny the access to the data center.
2.1.2 Right after the onion peel, protecting the servers
Once the onion is peeled, in other words, once access to the data center is in place, it is time
to establish the security of the servers and consoles in the data center. Not necessarily
everyone that accesses the data center must have access to all server consoles in the data
A preferred practice is that all server consoles have a way to request authentication to be
unlocked for use. It can be an authorization method to unlock the screen, if just an
administrator user ID is used at the console, or an user ID authorization and authentication
method to make sure that the person accessing the console has the correct privileges to the
server, considering the operating system has a separation of privilege classes for user ID.
2.1.3 To the frying pan, when data physically leaves the data center
Before moving on in the analogy of onion layers to the bits level, it is important to know how to
carry some pieces of it to the frying pan, in other words, how information physically leaves a
data center and how it must be protected.
There are basically two ways the information physically leaves a data center. First is when
moving machines to another building or data center. Second is when moving backup media
A good backup policy follows at least what is known as the three-two-one rule. Keep three
copies of the files, the original and two more backup copies, store the backup copies on two
different media types, such as hard drives and magnetic tapes, and last but not least, keep
one backup copy offsite, and really offsite, not in the next door room, because in case of fire
or flood in the data center building, the original data, the second copy of the data, and the
third copy of the data will be damaged.
Following a good backup policy, media will leave the data center with data backup. This media
needs to be protected in case of unauthorized access to read the data. A good approach is to
encrypt the data on this external media. This will often prevent unauthorized access to the
content of the media and protect the information on the media.
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2.2 Inside the bits protection
Going further along with the layered analogy of the onion, with the physical security of the
hardware in place, now it is time to secure the logical information, the bits. At this point there
are different layers that need to have security in place.
Starting from the server side, the operating system needs to be secure, the application needs
to be secure, the database needs to be secure, and then the communication between the
client and the server needs to be secure. Securing the communication is important to keep
the integrity of a request and the integrity of the data going through the communication.
2.2.1 Operating System Security - The Hypervisor
Hypervisor security will not differ from the security of any other operating system on a server,
but an important fact is that the virtual infrastructure relies on the security of the hypervisor,
so protecting the hypervisor (in either IBM z/VM or KVM) will typically cover attempts to
breach the security of the operating system and attempts against inadvertently compromising
the integrity of the operating system and data.
While each guest may have its own security configuration and faces threats particular to it, it’s
essential to protect the hypervisor istself as an equally important part of an overall end-to-end
security policy as actions like create, change, and remove virtual machines are performed at
the hypervisor, access to the virtualization management system should be restricted to
authorized administrators only.
The work to maintain the hypervisor is part of the system administrator role. Depending on
the infrastructure size of the organization, the role of hypervisor system administrator and
guest system administrator are separated.
The hypervisor system administrator must ensure the hypervisor is secure. One of the
practices is always keep the hypervisor up to date with corrections. Installing the corrections
as soon as released decreases the time frame the vulnerability can be exploited. Use of
centralized patch management solutions helps with the increase in number of hypervisors
managed on an IT infrastructure.
Another practice that helps avoid undesirable problems is disconnect or undefine unused
physical hardware from the hypervisor and disable all unnecessary services on the
hypervisor operating systems. This decreases the number of vectors an attacker can use to
get access, attempt to breach, or compromise the hypervisor and, subsequently, the
operating system.
Besides operating system set up and customization for security, monitoring the hypervisor for
signs of compromise helps to promptly respond to a threat. There are monitoring tools that
help monitor the hypervisor and also look at the hypervisor logs for suspicious activities
making the work of the hypervisor system administrator easier.
During the infrastructure planning, a practice that helps securing the hypervisor is separate
the hypervisor network and its guests network. If possible, restrict the hypervisor network to
administrative teams using a dedicated management network or encrypt the management
network communications to the hypervisor operating system.
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2.2.2 Operating System Security - The Guest
A guest operating system running on a virtualized environment does not differ from an
operating system running on real hardware in terms of security. The same security
considerations that apply to operating systems running on real hardware also apply to the
guest operating systems running in a virtualized environment.
In this case all recommended practices for managing operating systems running on real
hardware such as update management, log management, authentication, remote access,
and user ID management, must be followed. Nevertheless, for the guest operating system
some additional security actions should be made.
The first action to secure guest operating systems is to disconnect any unused virtualized
hardware. An example of unused virtualized hardware that may expose the guest operating
system is a network adapter or a removable media drive. Removing the unused virtualized
hardware is important to reduce the vectors an attacker can use to attempt to breach, get
access, or compromise the guest operating system.
Another action use to secure your guests concerns shared disks among the guests. If one of
the guests is compromised, the shared disk can be used to compromise the other guest
systems that access the same shared disk. If the organization includes rules for shared
network attached storage access in the information security policy, these rules should apply
to the shared disks on a virtualized environment as well.
If the guest systems are not related to each other, for example, if they are used by different
customers, it is important to, at the very least, separate the authentication methods for them
to make sure users are not authorized to authenticate on guest systems they are not
supposed to use. A preferred solution is to separate customer guest systems on different
networks altogether.
2.2.3 Application security, protecting the database server
Basic database security measures like authentication, authorization, and access control are
not enough anymore due to the growing number of sophisticated attacks. It is not an unusual
situation where a database administrator discovers a security breach long after it happens.
Before implementing database security, it is important to plan and know why the database
must be protected. The following are some examples of securing the organization databases.
򐂰 Understand applicable regulatory compliance standards such as from the European Union
(EU), Health Insurance Portability and Accountability Act (HIPAA), Payment Card Industry
(PCI) and Sarbanes-Oxley (SOX).
򐂰 Know what data must be protected, such as credit card information, employee information,
customers information, projects information.
򐂰 Make a list of all databases within the organization, including those used for testing and
򐂰 Classify all the listed databases as highly sensitive, sensitive, and nonsensitive.
򐂰 Establish the policies that must be applied to each category of database. Depending on
the category and as needed, implement advanced security measures such as firewall,
encryption, masking, auditing, and monitoring.
򐂰 Integrate the database policies with the organization information security policy.
These actions can be defined using the three main pillars for enterprise database security:
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򐂰 Foundation, the starting point for a database implementation strategy.
– Discovery and classification of databases.
– Authentication, Authorization and Access Control.
– Patch management.
򐂰 Preventive, make sure the database is healthy.
– Change management.
– Data masking.
– Network communication and data at rest encryption.
򐂰 Detection, always be aware of what is happening.
– Vulnerability assessment.
– Security monitoring.
– Database auditing.
2.2.4 Application security, protecting the application server
An application server is used to host business logic and data access services. It may be part
of the graphical user interface front-end, but it is recommended to have it separated, between
the front-end and the database to provide even more security. There are four basic
approaches to attacking an application server1:
򐂰 Network-based attacks: These attacks rely on low-level access to network packets and
attempt to harm the system by altering this traffic or discovering information from these
򐂰 Machine-based attacks: In this case, the intruder has access to a machine on which
WebSphere® Application Server is running. Here, Your goal is to limit the ability to
damage the configuration or to see things that shouldn't be seen.
򐂰 Application-based external attacks: In this scenario, an intruder uses application-level
protocols (HTTP, IIOP, JMX, Web services, and so on) to access the application, perhaps
via a Web browser or some other client type, and uses this access in an attempt to
circumvent the normal use of the application usage and do inappropriate things. The key
is that the attack is executed using well-defined APIs and protocols. The intruder is not
necessarily outside the company, but rather is executing code from outside of the
application itself. These types of attacks are the most dangerous, as they usually require
the least skill and can be done from a great distance as long as IP connectivity is
򐂰 Application-based internal attacks (also known as application isolation): In this case, you
are concerned with the danger of a rogue application. In this scenario, multiple
applications share the same WebSphere Application Server infrastructure and you do not
completely trust each application.
The Java EE specification and WebSphere Application Server provide a powerful
infrastructure for implementing secure systems. Secure Socket Layer/ Transport Layer
Security, or SSL/TLS, (hereafter referred together as SSL) is a key component of the
WebSphere Application Server security architecture, used extensively for securing
communication. SSL is used to protect HTTP traffic, IIOP traffic, LDAP traffic, MQ traffic,
JDBC traffic, messaging traffic over the SIBus between WebSphere messaging engines, J2C
and SOAP traffic. SSL requires the use of public/private key pairs, and, in the case of
WebSphere Application Server, these keys are stored in key stores.
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The combined benefits of IBM Java 8 and z13 features – including Single Instruction Multiple
Data (SIMD) vector engine, simultaneous multithreading (SMT) and improved CP Assist for
Cryptographic Function (CPACF) – are providing up-to 2X improvement in
throughput-per-core for security-enabled applications and up-to 50% improvement for other
generic applications.
Application serving with SSL exploits the new Java 8 Clear Key CPACF and SIMD vector
instructions for string manipulation.
2.2.5 Communication security
In previous sections the main discussion was about how all layers are individually secured to
keep data integrity, data confidentiality and data availability at the source.
Security in individual layers may be enough to keep the data integrity, confidentiality and
availability at the destination, but it is important to secure the data while it is in transit, during
Using the z13 cryptographic hardware, you gain security from using the Central Processor
Assist for Cryptographic Functions (CPACF) and Crypto Express5S through in-kernel
cryptography APIs and, for Linux on z Systems, the libica cryptographic functions library. The
benefits of using these features are:
򐂰 File system encryption
򐂰 Communication encryption (to the applications such as IBM HTTP Server)
򐂰 System security by providing advanced cryptographic functions
There are some solutions can be implemented at the client side, but the organization can not
rely on client side only security. A user can forget to update his security software or security
operating system updates, can unconsciously install malware on his device that will prevent
the execution of the security software, or the user just does not install the security software.
What the organization can do is make sure the communication between the client and the
server is encrypted with a secure cryptographic protocol. New vulnerabilities are often
discovered on cryptographic protocols, cipher algorithms, and protocol implementation, so
the security team need to be up to date about what is currently secure to be used and new
vulnerabilities that need to be mitigated as soon as reported.
The IT infrastructure inside the organization is the responsibility of the organization, so all
means to avoid security breaches are valid to protect the information. A well planned network
infrastructure also helps securing the data communication. The first point of contact with the
Internet should be the network security system. It controls the incoming and outgoing traffic to
the organization’s network based on the application set of rules.
Separating the network in layers helps protecting the information, so during network
infrastructure planning it is important to consider at least a layer for a demilitarized zone, a
layer for the web servers, a layer for the application servers, and a layer for database servers.
This is not a rule and can be structured in different ways, but layering the network is important
and must be considered when planning the network infrastructure.
Installing intrusion detection systems assists in monitoring for attacks and helps parse audit
logs, that may use a large amount of storage and have a huge amount of information that a
human will not be able to read and find a pattern for an attack at the same time it is
happening. Intrusion detection systems will help system and network administrators detect
attacks and alert them about it while it exposes the techniques in use to exploit possible
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Chapter 2. Security Overview
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Chapter 3.
Use case
To keep the integrity of data in our system, it is important to secure all devices that serve as a
path or store the information such as a mobile device and web browser used as an interface
to the system, the network infrastructure that connects the client to the server, the hypervisor
and guest operating system that will hold the application server and the database server, and
also protect the backup media.
In this chapter we introduce a typical business scenario of a fictional company securing both
a website and a mobile application. We describe the business and technical requirements for
end-to-end security using z Systems from the systems of record through the systems of
engagement on out to your mobile application.
© Copyright IBM Corp. 2014. All rights reserved.
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3.1 Use case description
Mainframe transaction processing systems (CICS®) and data management products (DB2,
IMS, and VSAM) are involved with most of the data stored on a mainframe. Recall from
Figure 1-1 on page 8, how you would have an application server in the systems of record that
could be used to serve data from the systems of record to the web as well as from the
systems of record to the systems of engagement and subsequently to your mobile
In this scenario, we describe a general insurance application, GENAPP. GENAPP is a mobile
application where a customer can perform the following functions:
򐂰 View insurance policies
򐂰 Apply for new Home, Car, or Endowment policy
򐂰 Start an insurance claim
The mobile application makes calls to the insurance application (GENAPP) which is a CICS
COBOL application that insurance company uses to create and manage customer and
insurance policy data. Note that the data flows from the systems of record (CICS) into the
systems of engagement.
For a detailed explanation of how to implement this use case, see Chapter 11 of IBM System
z in a Mobile World Providing Secure and Timely Mobile Access to the Mainframe,
3.1.1 General architecture and transaction flow
Figure 3-1 demonstrates the architecture and transaction flow of the GENAPP mobile
Figure 3-1 Insurance application architecture and transaction flow
The mobile application user logs into the application
IBM MobileFirst application receives request
IBM MobileFirst application calls security test
IBM MobileFirst adapter transforms mobile request and calls CICS to retrieve customer
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5. CICS web service framework converts the request to the channel interface of the
GENAPP application
6. GENAPP Cobol application processes the insurance policy request and queries the
GENAPP database
7. Policy data is returned to the mobile app
In terms of security, IBM MobileFirst facilitates user authentication and integration into
existing security systems. It provides an integration with back-end applications, systems and
services. Existing applications and database management systems can be accessed directly
through common service orientated architectures and connectors provided by the IBM
MobileFirst platform.
Mobile security implementation requires a strategy for securing three levels (see Figure 3-2):
Mobile device management - secure the endpoint device and its data, including the
mobile application itself. In this case, GENAPP.
򐂰 The network or channel - authenticate, encrypt, monitor and manage, control and block
򐂰 The mobile application- secure access to the enterprise applications and data
Figure 3-2 Securing three levels for mobile security
Figure 3-3 depicts how risk mitigation controls for mobile security need to be deployed at all
three levels.
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Figure 3-3 Mobile security architectural overview
3.1.2 Mobile device management
To manage devices and enforce corporate security policy, organizations use mobile device
management (MDM) platforms. The MDM platform can also perform policy compliance
assessments, device wipes, application management, and device lockdowns. Organizations
that want to manage mobile devices typically require their employees to install an agent or a
mobile application embedded with a management agent. Each user then has to register and
activate the device before it can be used for business. Given the management resources
required, self-management capabilities can be offered to the employees to improve the
responsiveness of the solution.
Mobile applications offer a host of possibilities for enterprises - but only if implemented
correctly and securely. In this section, we discuss securing your mobile applications.
MDM solutions help organizations manage multivendor mobile devices through a central
console, and help to enforce good practices such as:
Password for user authentication
Automatic locking if the device is idle for a certain period of time
Anti-virus software and signature updates
Auto wipe or erasing of data after a certain number of failed password attempts
Self-service to remotely lock, locate, or wipe sensitive enterprise data on a device if stolen
or lost
򐂰 Securing sensitive enterprise data by using, for example, encryption, containerization, or
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An emerging trend when deploying a mobile device management solution is to segregate the
personal profile and the business profile on the mobile device, and to manage only the
business profile.
IBM MaaS360 is one comprehensive enterprise MDM platform that can provide end-to-end
support for users, devices, emails, apps, documents and web access.
For more information on the various approaches to mobile device management, see Securely
Adopting Mobile Technology Innovations for Your Enterprise Using IBM Security Solutions,
REDP-4957 as well as IBM System z in a Mobile World Providing Secure and Timely Mobile
Access to the Mainframe, SG24-8215.
3.1.3 Securing the network
When using enterprise applications, mobile users must have secure connections into the
organization, and there must be adequate protection to keep the perimeter secure. A central
location to manage and control access into the organization makes it easier to control and
manage secure entry.
By implementing a mobile systems of engagement on z Systems, with access to a systems of
record as z Systems back-end services and data, an entire network topology can be
virtualized on the z Systems platform. The official certified high isolation level for z Systems
and the virtual server that it can provision, enable the simplification of the entire network
without an impact to the overall network security.
There are a number of advantages in flattening the network for any end to end application
services on z Systems. This is particularly true for mobile applications due to the high traffic
In this section, we discuss the various ways of securing your z Systems network.
The heterogeneous environment on z Systems can be connected with the z Systems internal
networks. There are three different types of z Systems internal networks between the
systems of engagement and systems of record as shown in Figure 3-4.
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Figure 3-4 z Systems internal network options
1. HiperSockets™ networks implemented in firmware
HiperSockets networks are within the physical z Systems server. You can define multiple
independent HiperSockets networks in a single z Systems machine.
2. Shared Open System Adapter(OSA)
The z Systems network cards, called OSA, are used to build networks between serverrs
and virtual images on z Systems and the enterprise networks.
3. z/VM virtualized networks with the VSWITCH function
The VSWITCH function in z/VM enables mapping of real networks into virtualized
networks, which defines a secured network simplification and centralized management of
a network topology. Multiple VSWITCH can be defined in a single z/VM environment which
represent hubs in isolated networks in the same z/VM virtualization layer.
Network security is a wide subject to be explored. Security on every network path must be
managed. It is possible to think about network security when connecting from the client
software, a Telnet client for example, to a z/VM administrator user ID, or when connecting
from client software, an SSH client for example, to an administrator user ID at a Linux on z
Systems virtual machine running on z/VM, or even when connecting to the insurance system
hosted on a Linux on z Systems virtual machine at a z/VM.
All of these types of network connections need to be secure to decrease the possibility of a
breach in the IT infrastructure of our insurance company exammple.
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During IT infrastructure planning it is important to make a decision on whether the network
access to the hypervisor systems will be the same as the network access to guest systems. A
preferred practice is to separate both networks, creating one for hypervisor management and
one for virtual machine management and the application access. If this is not possible, at
least keeping an encrypted connection to the hypervisor systems is necessary.
Network access to z/VM
Considering the z/VM network is in the same network at the guest systems, use of encrypted
communication can be used to increase the security of the IT infrastructure for the insurance
company. By default, Telnet 3270 session data flows unencrypted over the network, in clear
text, meaning that anyone that dumps the network traffic is able to see what is happening
between the Telnet client and the z/VM guest console.
Transport Layer Security (TLS), and its predecessor, Secure Sockets Layer (SSL), are
cryptographic protocols to provide end-to-end encrypted communication. Digital certificates
and trust hierarchies can be implemented to make use of encrypted communication.
When talking about SSL/TLS for z/VM, SSLSERV is a CMS service machine that provides
encrypted communication to clients connecting to z/VM. Its code is pre installed as part of
standard z/VM installation and can be customized and enabled to provide SSL/TLS
It is also possible to use z/VM FTP server for file transmission from a client software to the
hypervisor and, by default, FTP server on z/VM do not accept any secure connection, but it is
possible to configure it to allow or require secure connections.
When using z/VM TCP/IP stack, different Service Virtual Machines (SVMs) can be set up for
different services, separating their functions related to specific protocol of support. As usual,
the preferred practice is to enable just services that will be used and make sure all security
recommendation are followed. Some examples of SVMs are the following:
򐂰 TCPIP service machine - for basic connectivity with the hypervisor using Transmission
Control Protocol / Internet Protocol (TCP/IP).
򐂰 FTPSERVE - for File Transmission Protocol (FTP).
򐂰 LDAPSRV - for Lighweight Directory Access Protocol (LDAP).
򐂰 MPROUTE - for communication route.
Most of the TCP/IP stack SVMs can have security controlled by RACF/VM. This allow
RACF/VM to process user ID connection authentication and authorization to the system and
to resources, increasing the level of security on the system.
More information about how to customize and enable SSLSERV service machine or configure
FTP server to accept secure connections can be found at IBM Redbooks publication Security
for Linux on System z, SG24-7728.
Network access to Linux on z Systems
To connect to a Linux server using encrypted communication, usually SSH protocol is used.
OpenSSH (OpenBSD Secure Shell) is a client-server application used to connect to Linux
servers that implement SSH protocol. It provides encrypted communication between the
client and the server and is developed as part of the OpenBSD project.
Configuring and enabling OpenSSH on Linux on z Systems improves the communication
security with the server when connecting to any system user ID. A simple setup will require
just an user ID and the password to authenticate, but it is possible to implement two factor
authentication, or make use of a public key infrastructure (PKI).
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Some implementations of PKI allows users to connect to Linux servers without a password,
requiring just the public and private key pair. A preferred practice is to setup PKI
authentication using passwords. It will prevent access to the Linux server in case an attacker
has access to a user private key but do not have the password.
As encryption may be costly to system performance, throughput, or processor load, starting
with OpenSSH version 4.4, it is possible to benefit from IBM z Systems hardware encryption
to reduce the impact of expensive encryption operations.
More information about OpenSSH configuration and enablement can be found at IBM
Redbooks publication Security for Linux on System z, SG24-7728.
Network access to the insurance system
When a clients need to connect to the insurance system in our use case, the information, or
data, that leaves the client’s device and reaches the insurance system on a Linux on z
Systems server needs to be protected against an attacker that wants to collect the data for
visualization or modify the data during the transmission.
Encrypting the communication between the client device and the application is usually used
to avoid the data traffic in clear text. Most application servers use SSL/TLS to encrypt the
communications with clients.
For IBM WebSphere Application Server security architecture, SSL/TLS is a key component. It
is mainly used to protect HTTP traffic, IIOP traffic, LDAP traffic, MQ traffic, JDBC traffic,
messaging traffic over the SIBus between WebSphere messaging engines, J2C and SOAP
SSL/TLS is also supported in IBM DB2 databases using JDBC and SQLJ drivers. Using a
secure DB2 database communication will improve overall IT infrastructure security of the
insurance company.
z/VM Connectivity
Using z/VM network virtualization brings a layer of security to data being transferred to its
guest systems. Queued Direct Input/Output (QDIO) architecture uses direct memory access
(DMA) to transfer network data from the address space of the sender to the address space of
the receiver. When using HyperSockets networks, this means that network traffic can not be
“sniffed” by other z/VM guests or other LPARs. Same happens with communication from
OSA-Express to the guest, network traffic is moved directly to/from the adapter to the address
space of the sender/receiver.
With a Local Area Network (LAN) configured on the hypervisor, it is possible to establish
communication through the guests without leaving the hypervisor layer. There are two ways to
set up a LAN on z/VM, using Guest LAN, where a global LAN segment is defined and guests
have a Network Interface Card (NIC) connected to the guest LAN segment, or using z/VM
Virtual Switch (VSWITCH).
A good practice is to disable TRANSIENT Guest LAN functionality as it allows user IDs
defined with Privilege Class G to create their own dynamic Guest LANs, creating a possible
breach of information flow control.
Use VSWITCH for LAN connectivity with the security options it offers. The routing of
packages, when using VSWITCH, are done at the hypervisor layer, removing the overhead of
a guest needing to act as a router, bringing performance benefits as well.
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VSWITCH supports Layer 3 (TCP/IP) or Layer 2 (Ethernet) modes and it is possible to define
it to use the same subnet of the external network to which it is connected. It also supports
IEEE 802.1Q VLAN, making the network management simpler with the use of VLAN subnets.
It is important to correctly set up the VSWITCH after the network infrastructure is planned. By
default, VSWITCH does not allow guests to couple to it, so guests need to be explicitly
allowed to couple to the VSWITCH. This helps control which guests have access to which
VSWITCHes, but granting the access carefully also prevents guests from accessing LAN
segments they are not supposed to have access. VLAN tagging helps keep control of this
kind of situation in addition to the creation of RACF/VM groups.
Using a VSWITCH access group and VLAN tagging can efficiently provide access control to
system resources, but are considered discretionary rules that must be carefully maintained to
avoid security breaches. The use of Mandatory Access Control (MAC) addresses the
management problem. MAC is a security policy that governs which subject or users can
access which resources, and in what way. MAC restricts access to an object verifying three
main rules:
򐂰 The security label assigned to the subject.
򐂰 The security label assigned to the object.
򐂰 The access the subject requires to perform a task.
If those three MAC criterias are met, z/VM proceeds with the discretionary access control
when appropriated.
The use of MAC create security zones, adding flexibility to system administrators when
managing the system resources. It is implemented activating security labels under RACF/VM.
More information on how activate and set up security labels can be found at IBM Redbooks
publication Security for Linux on System z, SG24-7728.
The use of VSWITCH for network management in conjunction with RACF/VM for security and
audit purpose gives z/VM hypervisor and guests a higher level of security while decreasing
the time spent to manage it.
More information about VSWITCH technology and its configuration, see the z/VM
Connectivity Guide, SC24-6174.
3.2 Securing the enterprise applications
It is critical for the the insurance company that only authorized requests are processed by the
CICS GENAPP application. In order to secure the connection from IBM MobileFirst to CICS in
our example, SSL mutual authentication is used.
SSL/TLS is a well understood and popular way to provide encryption and data integrity. It can
also be used to enable both server and client authentication.
Server authentication with CICS requires CICS to have an X.509 certificate stored in the
CICS region’s certificate key ring. The certificate (which we refer to as the CICS server
certificate) is used as part of the SSL handshake processing. The client, in this case an IBM
MobileFirst Server, validates the CICS server certificate. Successful server authentication
requires that the Certificate Authority (CA) that signed the CICS server certificate be
considered trusted by IBM MobileFirst. To be considered trusted, the certificate of the CA
must be in the keystore of the client.
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To use mutual authentication, the IBM MobileFirst Server must have a client X.509 certificate
(we will call this the IBM MobileFirst client certificate). The CICS region validates the IBM
MobileFirst client certificate. Successful client authentication requires that the Certificate
Authority (CA) that signed the IBM MobileFirst client certificate be considered trusted by
CICS. To be considered trusted, the certificate of the CA must be in the key ring of the CICS
CICS uses the z/OS system’s SSL (a component of z/OS Communications Server) to support
both the SSL and TLS protocols.
Additional considerations to secure your enterprise applications include:
Certificate and RACF user ID checklist
Certificate and user RACF ID checklist
Enable SSL
Enable SSL mutual authentication
Optimize SSL performance
See Chapter 11 of IBM System z in a Mobile World Providing Secure and Timely Mobile
Access to the Mainframe, SG24-8215 for more information regarding these considerations.
3.3 Operating system security - z/VM
As z/VM is a hypervisor and an operating system at the same time, most security practices
that apply to a traditional operating system will apply to z/VM, but some considerations need
to be made when looking at it as a hypervisor.
The main consideration concerns what should be protected at the z/VM level. Planning must
be done to protect all known points of failure. One would thinkn that the virtual machines
(guests) must be protected, but as z/VM is the hypervisor, protection of the Control Program
(CP), the core of z/VM, needs to be in place. Data security is also a consideration and
protection need to be in place while it is transferred through the virtual network of z/VM and
when it is stored on a disk, or on backup media.
Using z/VM as the hypervisor to virtualize an IT infrastructure enables the organization to
mainly manage the servers using universal management tools, reducing costs related to
server management, and maximizing the utilization of IBM z Systems hardware.
Although z/VM can be installed alone as a unique Logical Partition (LPAR) on a machine to
virtualize the z Systems hardware, it is also possible to run z/VM in an LPAR and other
operating systems on different LPARs, such as z/OS, z/VSE® and Linux for z Systems. While
used to virtualize the z Systems hardware, z/VM can either virtualize the same z Systems
server it is running on or emulate hardware features not necessarily available on its hardware.
It is possible to use z/VM to provide a customized environment for each guest, giving them z
Systems features that are accessed simultaneously without the need of a real physical server
for each guest, or z/VM can handle access to the real devices for each guest as needed.
An advantage of using z/VM to virtualize the IT infrastructure is that the number of guests on
z/VM is limited to the amount of resources available on the z Systems on which it is installed.
In this case, the environment can be set up to use the most hardware resources z Systems
can provide.
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More information on z/VM security beyond this section can be found in the IBM Redbooks
publication Security on the IBM Mainframe, Vol. 1 A Holistic Approach by Reducing Risk and
Improving Security, SG24-7803.
3.3.1 Virtual machine security
As z/VM is a virtualization hypervisor, its main task is to handle multiple guests sharing z
Systems resources at the same time. It is important to keep guests’ workloads separate, so a
guest cannot threaten the integrity of either another guest or the hypervisor itself. This
concept is called guest isolation and begins at the instruction level, so most instructions are
executed by z Systems hardware with little intervention from z/VM.
The Start Interpretive Execution instruction (SIE) on z Systems creates the environment for
the guests. It will handle the use of region, segment, and page tables that were set up
previously by the z/VM Control Program for the guest. SIE instruction is exploited by z/VM to
decrease the overhead of the Control Program and is available only with z Systems hardware.
Guest isolation only separates one guest from another. To secure the guests within a z/VM
environment, it is necessary to define the scope of responsibility for each guest. A guest must
only have access and authority to perform functions required by hosted workload, always the
least access and authority needed, no more, no less.
Privilege classes
The first step to limit access and authority for guests is plan the privilege classes. A guest can
have one or more privilege classes defined to it and the privilege classes that the guest are
assigned represents a job or role associated with that guest workload.
By default, z/VM has seven privilege classes, represented by letters from A through G. The
default class with the least privilege is class G, known as the General User class. Classes
greater than G are usually assigned to privileged users.
It is possible to create new privilege classes. This can increase the security of z/VM virtual
environment and will be in accordance with your guest role definition. These classes are
created by the z/VM system administrator and will meet the information security policy and
the roles defined for guest workload. Custom privilege classes are represented using letters
from I to Z, or the numbers 1 through 6.
There are cases that a command can affect more in the hypervisor than is expected for the
guest. An example is the command ATTACH from Privilege Class B used to attach a real device
to an ID in z/VM. A guest may need to sporadically issue the ATTACH command to be able to
use a specific real device, but if this command is available in a custom class, the guest will be
able to attach any real device defined in z/VM, meaning the guest can attach disks for other
guests, as an example.
One way to overcome this breach is by using the COMMAND directory statement. In the guest’s
user directory it is possible to specify the exact command the guest is authorized to issue.
The following is an example COMMAND directory entry:
In this case, the guest will be able to issue just the ATTACH command specified in its directory.
It will be able to only attach real device address F000 to guest ID LNXSRV10 as a virtual address
of D000 avoiding the exposure of all other real devices defined in the z/VM hypervisor.
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A z/VM feature that is very useful for system administrators is the LOGONBY directory entry.
Using it in the directory for the guest definition it is possible to authenticate to this guest ID on
z/VM using an authorized z/VM user ID and its password. The following is an example of how
the login command is used to authenticate to a guest:
The password or password phrase for z/VM user ID WILLIANR is required in order to
authenticate with the LNXSRV10 guest ID and not the password or password phrase for
LNXSRV10. This helps keep track of who accessed guests in case there is a team of
administrators, providing accountability for access.
This functionality is extended to RACF/VM using the SURROGAT class of operation.
3.3.2 Hypervisor security
Using z/VM as a hypervisor gives Linux on z Systems valuable security and integrity features.
Mainly, z/VM provides flexibility when consolidating servers while protecting the environment
with multiple security zones. Running Linux as a guest on z/VM provides the best way to gain
the maximum benefits from the z Systems platform.
The core functionality of z/VM has been enforcing system integrity and guest isolation. It is
important to review hypervisor configuration and customization before deployment.
Sometimes the default configuration is not enough to comply with the organization’s
information security policy. A review of the z/VM system configuration file is a good start right
after z/VM installation.
System Configuration file
The z/VM system configuration file, SYSTEM CONFIG, defines attributes of the z/VM system
at IPL time. Within the z/VM system configuration file it is possible to customize basic default
settings of the hypervisor to comply with an information security policy.
It is possible to change the Privilege Classes commands discussed in “Privilege classes” on
page 29 and, for example, increase or decrease the privilege of a General User Class (Class
G), or a System Operator Class (Class A) or even create a custom Guest Server Class (Class
from I to Z, 1 to 6) with specific commands allowed for use by the guest servers.
This cannot be done using the MODIFY COMMAND or MODIFY DIAGNOSE statements in the z/VM
system configuration file. These commands can redefine the existing CP commands and
diagnoses instructions from their default privilege class to another existing or custom privilege
classes(among other things). The main advantage of these commands is to remove
potentially dangerous commands from use before deployment.
As an example, the SHUTDOWN command is defined with the IBM default privilege class A, the
System Operator class. This command can be moved to a new Privilege Class to avoid its
use by mistake. The following demonstrates an example of how this command can be
This command will remove the SHUTDOWN command from privilege class A and place it in
privilege class S. The SHUTDOWN command is used to shut down the entire z/VM LPAR and
because it is so disruptive, it is important that the information security policy restricts it to only
the few roles that will need to use privilege class S.
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Another security setting that needs to be reviewed is TDISK_CLEAR, which will purge temporary
disk space as soon as it is released back to the hypervisor. This will prevent guests from
reading what was written in the temporary disk by other guests when the temporary disk is
not used anymore and released.
There is a command defined in privilege class C that allows a user ID to escalate a privilege.
This command is the SET PRIVCLASS. When a guest has access to privilege class C, this guest
can use SET PRIVCLASS to escalate its privilege to any other privilege class defined at the
z/VM system configuration file. This means that a guest with access to this command can
actually issue any command at the hypervisor escalating its privilege.
The z/VM system configuration file has a setting that allows the use of SET PRIVCLASS
command, enabling or disabling it. The setting is called SET_PRIVCLASS and must be reviewed
before the z/VM deployment.
In the z/VM system configuration file, the use of the JOURNALING statement enables the
system to log CP commands in the journaling records. This statement is useful when
RACF/VM is not enabled on the system. Journaling options will be discussed in section,
“Monitor system logs” on page 32.
The user directory
The user directory holds the definitions for all virtual machines on z/VM. When a directory
manager is not enabled, this file is updated manually and changes are put into place using
the DIRECTXA CP command. To be able to issue this command, the user ID needs to have
privilege class A, B or C, so updates to the user directory is usually assigned to the system
administrator role.
Without using an External Security Manager(ESM), user ID passwords and minidisks
passwords are also manually managed in the user directory. In the machine-readable binary
directory space, the passwords are kept in an encrypted format, but the source file holds all
passwords in clear text format. Again, update of the user directory is usually assigned to the
system administrator role so exposure is limited, but a system administrator is also the only
person that can set passwords on the system.
Managing the user directory manually can be time consuming depending on the number of
hypervisors and virtual machines. To reduce the time spent managing the user directory and
avoiding mistakes done manually, it is recommended enabling a directory manager.
The IBM z/VM Directory Maintenance Facility (DirMaint™) is a collection of service virtual
machines that control and manage changes to the virtual machine and hypervisor definitions.
These virtual machines will work as a focal point for directory-related operations assuming
the control of the user directory.
Enabling DirMaint allows for an additional mechanism to protect virtual machine definitions.
User directory statements can be added, deleted, or altered using DirMaint while it provides
automated validation and extent allocation routines to reduce the chances of system
administrator error.
Because DirMaint service machines have privileges through specific privilege classes to
change the user directory, access to DirMaint commands must be controlled through its
configuration files, and only system administrators or roles defined in the information security
policy must have access to it.
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Update management
As described on 2.2.1, “Operating System Security - The Hypervisor” on page 13, keeping
the operating system updated will prevent exposure. APARs labeled as SEC/INT are mainly
important to keep system security and/or integrity and should be applied as soon as possible.
Use of centralized patch management tools helps to keep track of updates applied and
updates missing while controlling all systems that are managed by it.
Furthermore, a well established update process will keep track of system updates and
manage them in an acceptable time frame. This ensures a more secure environment for the
Monitor system logs
Customize the z/VM system and keeping it updated are necessary steps to grant a more
secure system, but can not be the only steps related to security. Periodically monitor the
system, keeping and examining audit trails must also be part of securing the hypervisor.
Most audit data will come from RACF/VM. It can audit every command and security-relevant
event that happens within the hypervisor, in accordance with the information security policy.
When RACF/VM is not enabled, it is possible to record actions on the hypervisor using the CP
command journaling options. The journaling will detect and record the occurrences of CP
commands that it is configured to monitor. Analyzing the recorded information makes it
possible to identify attempts to access a resource or log on the hypervisor.
Some jounaling options are LOGON, AUTOLOG, XAUTOLOG, and LINK. These are
responsible for recording information about the use of CP commands LOGON, AUTOLOG,
XAUTOLOG and LINK. It is possible to set up CP to take preventive actions based on the
number of attempts a user ID has tried one of those CP commands. The following are the
actions CP can take:
򐂰 Record the incident in the accounting data set.
򐂰 Reject any new attempts to use that CP command (related to the journaling option).
򐂰 Lock the terminal for a certain amount of time.
򐂰 Send a message to the user ID.
External Security Managers
An External Security Manager (ESM) is a key component of virtualization security at the
hypervisor layer in modern environments. RACF Security Server (RACF/VM) is a priced ESM
for z/VM and will provide a centralized and effective security mechanism for authentication
and authorization of users to access system resources.
Usually an implementation of a virtualized environment on z/VM without planning starts
without the use of an ESM, but further, with a couple of Linux servers deployed it becomes
clear that an ESM is required to support the environment. The following are some reasons to
plan for using an ESM before deploying the guests.
򐂰 Regulatory compliance - Organizations that must comply with government and industry
regulations for controlling and managing customer and client data require a level of
security beyond that provided by just the z/VM internal security mechanism.
򐂰 Audit capability - An ESM will be able to create clear audit reports, that are often required
by government and industry customers. Manually creating an audit report can be time
consuming without the use of an ESM.
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򐂰 Advanced security features - Use of an ESM centralizes the security administration of all
system resources. It provides access to detailed configuration attributes and a better
control over the entire system.
򐂰 Consistency across multiple z/VM systems - It is possible to manage multiple hypervisors
using a centralized ESM database to hold all security configurations. This kind of
configuration provides a bird’s-eye-view of the entire virtualization infrastructure.
The advantages of using an ESM include:
򐂰 Overrides base CP security functions giving more detailed options to control the security
over system resources.
򐂰 Encrypts virtual machine passwords and stores it on a database, replacing the user
directory password.
򐂰 Supports password phrases with mixed-case ranging from 14 to 100 characters in length.
򐂰 Allows for greater control over CP commands, adding detailed options of control.
򐂰 Allows for Discretionary Access Controls (DAC)- access list for resource use.
򐂰 Allows for Mandatory Access Controls (MAC)- security labels that group system
With RACF/VM it is possible to control privileged VM commands. It is possible to enable a
resource class called VMCMD and create profiles to control the commands needed. As an
example, it is possible to create a profile for the SHUTDOWN command with a Universal Access
(UACC) of NONE. That way the command is disabled by default. Even if a virtual machine has
access to Privilege Class A, if this machine is not listed in the SHUTDOWN profile in the VMCMD
resource class, this virtual machine is not allowed to successfully execute a SHUTDOWN
command providing the advantage that resource classes and profiles are properly audited.
Furthermore, RACF/VM allows for auditing of any security-relevant event on the system. Most
auditing options on RACF/VM are disabled by default, so it is a good practice to list the control
and auditing settings and enable all options that will comply with the information security
It is also possible on RACF/VM to create labeled security zones with Mandatory Access
Controls. That way groups of system resources can be labeled and access granted to the
necessary virtual machines. Without an access granted, a virtual machine can not access a
system resource defined at a security label even if this virtual machine has access to the
Access Control List of that single system resource. In short, Mandatory Access Controls will
turn possible access to a resource in deny of access to the resource.
This concept, referred as multi-tenancy, allows creation of multiple security zones within the
hypervisor without the possibility of contamination between different virtual machines.
Enabling RACF/VM complements and extends basic z/VM security features while providing
more granularity and accountability of all accesses and operations events. Its access control
includes user verification, resource authorization, and logging capabilities. Enabling
RACF/VM requires customization, so it can comply with your information security policy.
User ID and password management
Whether or not you have an ESM enabled, it is a good practice to have in the information
security policy user ID and password management rules.
Make sure the user IDs defined on the system comply with the user ID management tool
used. It is a good practice to not allow the use of punctuation or symbols and also do not use
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system keywords (like command names, command operands or 1 to 4 digit user IDs that
could be spool IDs). Results using any of these options as user IDs are unpredictable.
For service machines that are not enabled or not used on the system, convert their directory
password to NOLOG to deny the ability to log on to those machines. If RACF/VM is enabled on
the system, revoke the IBMUSER user ID and remove all of its privileges.
Add to the information security policy the password rules for the user IDs. Some suggestions
for password rules include:
򐂰 Enforce changing the password when the user ID is first created with a default password
򐂰 Enforce changing the password periodically(for example, every 180 days),
򐂰 Explore the use of passwords with mixed case and use of numbers.
A good password management policy will help prevent security incidents.
Improving security management
Having RACF/VM enabled plays a vital role in helping to protect the hypervisor. When the
number of hypervisor systems increase in a data center, even the use of RACF/VM as the
centralized ESM can become complex and time consuming, requiring an increase of skilled
IBM Security zSecure™ Manager for RACF z/VM can help system administrators on their
daily tasks. It automates many recurring system administration functions like adding or
deleting user IDs and groups, defining and granting access to users and groups, setting and
resetting user IDs and passwords, running daily or monthly reports. This reduces errors,
minimizes complexity, improves quality of service, demonstrates compliance with the
information security policy and reduces costs.
Security zSecure Manager for RACF z/VM can be automated to repeatable audit the
hypervisor and RACF/VM database and create reports without the need of daily manual
intervention from system administrator. This reduces the time spent by the system
administrators on creating reports and give them time to analyses the reports, that will
automatically have security concerns highlighted and prioritized
The reports created by Security zSecure Manager for RACF z/VM will also show missing or
inconsistent definitions, decreasing the time to fix or prevent mistakes before they become a
threat to security and compliance. It also includes a powerful system integrity analysis feature
that can help reveal breaches in system integrity.
On the virtual machine side, Security zSecure Manager for RACF z/VM includes support for
auditing events from Linux on z Systems. Auditing these event records helps detect Linux
security threats and creates compliance reports for Linux systems.
3.4 Data security
As discussed previous, for most of the organization, information can be the most valuable
asset, so protecting it is important for the organization’s business. In section , “Network
access to the insurance system” on page 26 we described how to improve the security of the
data in flight, flowing through a network. It is also important to discuss the security of data at
rest, the data that is stored on a disk or backup media.
Data protection starts at the planning stage and goes right through to daily use on production
servers. The first place to define the accesses of a disk is during the definition, during the
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Input/Output Control Program (IOCP) set up.The IOCP definition handles the physical
resources, including disks, to which an LPAR will have access.
Depending on the amount of disks the LPARs on a CPC have access, the complexity of
defining each disk to be visible to just a single LPAR increases and it becomes costly. For this
reason, usually the IOCP definition is done with all LPARs on a CPC being able to access
almost every resource in the environment. The security is defined at a high level, with an ESM
like RACF/VM, or an application security. Although this decrease the complexity during the
IOCP definition, it increases the complexity at a high level, during RACF/VM definitions. It is a
trade-off that needs to be decided during the IT infrastructure planning.
When using Storage Area Network (SAN) volumes over Fibre Channel Protocol (FCP)
techniques such as zoning and LUN masking are essential for controlling access to SAN
volumes, specially in a heterogeneous computing environment where devices from many
manufacturers, using significantly different security architectures, all connect to the same
After the disk is defined and available to the LPAR, it is time to secure the minidisks. It is
important to define minidisk access just to the users they are intended for. Information can be
leaked between virtual machines when a minidisk has its access too lax, mainly if virtual
machines from different security zones has access to it.
Although minidisk password defined on the user directory can protect the access to the
resource, it falls under the discussion about directory management from “The user directory”
on page 31. The preferred practice is to use an ESM, like RACF/VM, to protect the resources.
As already discussed, an ESM provides greater granularity to access authority, and extensive
options for controlling auditing of both successful and unsuccessful accesses.
Controlling the access is also valid for shared disks. If there is a need to share files with
multiple virtual servers, a preferred practice is to make this shared disks read-only and allow
just one virtual machine to update it, reducing the risk of file corruption when multiple virtual
machines try to write to it and also the risk of a compromised virtual machine try to use the
shared disk to spread a malware over it.
Protecting the access to the disks is important, but another way to improve data security is
encrypting it. As encryption depends on a key, proper handling and implementation of a key
management policy is important. Failing on encryption key management can result in an
encryption deadlock and permanent loss of all encrypted data.
The use of encryption on z Systems leverages advantages through the use of cryptographic
hardware and cryptographic functions that are built-in the central processor, like the Central
Processor Assist for Cryptographic Function (CPACF). It will handle the cryptographic cipher
calculations, leaving the central processor available for other uses and considerably reducing
the central processor cycles when compared to the same cipher calculations done using
software emulation.
Using tools to encrypt the Linux on z Systems can increase the data security. The dm-crypt
subsystem in Linux is implemented as a device mapper that can be stacked on the top of
other devices that are managed through the device mapper framework, meaning it is possible
to encrypt from entire disks to software RAID volumes and LVM logical volumes, adding
flexibility to the encryption strategy.
For more information and steps on how to encrypt data on disks using dm-crypt refer to IBM
Redbooks publication Security for Linux on System z, SG24-7728.
Last but not least, it is important to remember that data on backup media must be encrypted.
It is a security breach if a backup media with sensitive information leaves the data center and
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others outside the organization have access to that media. Protecting the data center and all
devices within it is important, but let the information leave the data center without being
protected is the same as ignore all protection implemented on the organization data center.
3.5 Operating system security - Linux on IBM z Systems
Running Linux on IBM z Systems servers bring some advantage over a server farm physically
distributed by using unique technologies leveraged by the platform hardening the overall
security. Following are some discussion on security topics that need attention when
implementing a Linux environment.
Authentication is the process of determining whether someone really is who he or she claims
to be. The users attempting to access a system or a resource must first give sufficient proof of
their identity. A server authentication is usually done using two of the following three
categories, or factors for providing identity:
򐂰 Something you know - a password or PIN.
򐂰 Something you have - a token, a user ID, a badge, a certificate.
򐂰 Something you are - biometrics characteristics.
The traditional way to authenticate on a Linux server is having a user ID on the system and
knowing a password of it. Implementation of more than two of the factors is already available
for Linux system, making it possible to request a user ID, a password and a PIN that is
generated by some electronic device, like a token or an application on a cell phone, when
authenticating. Use of more factors for authentication brings a high level of security to what is
being accessed.
The Pluggable Authentication Modules (PAM) can be used to reinforce compliance with the
organization information security policy by increasing the number of factors used to
authenticate and only allowing access to user meeting the specific characteristics defined
with PAM. Applications that are enabled to make use of PAM can be plugged into new
technologies without modifying the existing applications. This flexibility allows administrators
򐂰 Make use of any available authentication service for an application.
򐂰 Use multiple authentication mechanisms for a given service.
򐂰 Add new authentication service modules without the need to modify the application.
򐂰 Use a single password for authentication on multiple modules.
Another factor that improves security level is the use of Public Key Infrastructure (PKI), like
SSH key pair. The user need to have a public and private key pair that ensures the user ID.
Although it is possible to use SSH key pair without a password set to it, the recommendation
is that a password is set to the key par. In case an attacker has access to the private key,
without knowing the password the user ID can not be authenticated at the server.
Access control
Defining each job role in Linux is complicated because everything converges to the root user
ID. However, doing so is a good practice by defining the access and having strong control
over who can access a superuser account.
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Discretionary Access Control (DAC) model, being the standard Linux security, does not
provide protection from broken software or malware running as a normal user or root. Users
can grant risky levels of access to files they own.
Use of Mandatory Access Control (MAC) provides full control over all interactions of software.
Administratively defined policy closely controls users and process interactions within the
system, and can protect from broken software or malware running as any user.
Security-Enhanced Linux (SELinux) on Red Hat Enterprise Linux (RHEL) is an
implementation of MAC using Linux Security Models, based on the principle of least privilege.
When enabled in permissive mode, every access to a system resource by a user or process
such as an I/O device must be controlled by SELinux. This can sometimes cause overhead
on the system.
AppArmor is a Linux application security framework included with Novell SUSE Linux
Enterprise and is an open source project. It takes a different approach from SELinux
providing a easy-to-use way for security applications at Linux. Following are some features
that can be found at AppArmor.
򐂰 Yet another Setup Tool (YaST) - administration tool for configuration, maintenance and
automated development of a per-program security policy.
򐂰 Predefined security policies for standard Linux programs and services.
򐂰 Robust reporting and alerting capabilities to facilitate regulatory compliance.
򐂰 Common Interface Model (CIM) - clients that integrate with industry standard
management consoles.
򐂰 ZENworks Linux Management integration for profile distribution and report aggregation.
򐂰 Path-name-based system that does not require labeling or relabeling of file systems
For more information on how to set up SELinux or AppArmor at Linux on z Systems, refer to
IBM Redbooks publication Security for Linux on System z, SG24-7728.
User management
When the IT infrastructure increases in its size, the number of user IDs also increases and
also the complexity on managing the user IDs. It is important to have a way to manage user
IDs, mainly for a security concern.
Centralizing the repository of user IDs helps in the management activities, reducing the
administration effort compared to distributed user IDs management. It is considered a good
practice for the maintenance of the information security policies that are applied to user
The centralization of user ID management involves mainly adding, deleting, changing account
information and, resetting passwords. Doing that from a single and centralized point, such as
an LDAP server, can help keep the security requirements and policies consistent throughout
the IT infrastructure, avoiding the need to spread sensitive information from users, like
passwords, to all servers.
When using a centralized user ID management server, it is important that all servers
connecting to it use an encrypted connection. Not necessarily all the information flowing
between the LDAP server and the servers on the IT infrastructure are sensitive information
and need to be protected, but enabling this protection is simpler to implement than using a
mixed of encrypted/non-encrypted connection.
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Update management
Keeping the operating system updated will prevent its exposure. A well established update
process under the servers will keep track of system updates and manage them in an
acceptable time frame. Using a minimal system installation will also help keep control of
security and system update. There will be less potential points of security exposure when less
packages are installed and managed.
The use of a centralized patch management tool can decrease the complexity and time spent
to apply server patches when the number of servers being managed increases. It also helps
to keep track of patches applied and patches needed to all servers managed, avoiding the
possibility to leave a server without the updates.
A well-defined information security policy is worthless if there is no way to assess whether the
policies are really effective, meaning it was adhered by all employees and they are playing the
roles they are expected to.
Keeping track of changes, authorized and unauthorized accesses is a way to make sure the
information security policy is followed. But again, with the increase on number of servers
managed on the IT infrastructure, the amount of audit data generated makes it impossible to
be analyzed by a human, find a threat and act on it while still happening. For that reason it is
important to define, during the planning stage of the IT infrastructure, which action must be
logged for audits.
The complexity in auditing is reduced when well defined roles are available at the information
security policy. Users under one role should not have access to override the mandatory
access controls and should not be able to manipulate the controls that are under the
jurisdiction of another job role. With the separation of duties, the functionality of the systems
and integrity of audit logs will not be compromised.
To create a separation of duties under Linux it is possible to use SELinux or AppArmor. If
those tools are not used or enabled, the task to control and determine user privileges become
more complicated. A preferred practice then is to use Sudo to control access to privileged
commands. Use of Sudo will ensure a better protection limiting the privileged commands a
user can issue and protecting root password from being shared with system administrators.
Use of Sudo also ensures audit of accountability for users issuing privilege commands.
Cryptographic hardware
Linux on IBM z Systems can benefits from the use of z Systems cryptographic hardware. It
supports the use of Central Processor Assist for Cryptographic Functions (CPACF) and
Crypto Express5S (latest available while this book was written) through the use of in-kernel
crypto APIs and libica cryptographic functions library. Use of these features can benefit:
򐂰 File system encryption.
򐂰 Communication encryption (to the applications like IBM HTTP Server).
򐂰 System security by providing advanced cryptographic functionality.
CPACF is available on every processor unit defined as a Central Processor (CP) and can be
explicitly enabled by using the enablement feature #3863, for no extra fee. It provides a set of
symmetric cryptographic functions that enhance the encryption and decryption performance
of clear-key operations for Secure Sockets Layer (SSL), Virtual Private Network (VPN), and
data storing applications not requiring a high level of security, such as Federal Information
Processing Standard (FIPS) 140-2 Security Level 4, when compared to the same operations
done using software emulation encryption.
End to End Security with z Systems
Draft Document for Review March 12, 2015 2:19 pm
The CPACF coprocessor on the IBM z13 has been completely redesigned and has better
performance when compared to the zEC12.
CPACF offers the following data encryption and decryption algorithms for data privacy and
򐂰 Data Encryption Standard (DES).
– Single-length key DES
– Double-length key DES
– Triple-length key DES (TDES).
򐂰 Advanced Encryption Standard (AES) for 128-bit, 192-bit, and 256-bit keys.
CPACF offers hte following hashing algorithms for data integrity:
򐂰 SHA-1: 160 bit.
򐂰 SHA-2: 224, 256, 384, and 512 bit.
For message authentication codes (MAC), CPACF offers:
򐂰 Single-length key MAC.
򐂰 Double-length key MAC.
For cryptographic key generation, CPACF offers Pseudo-random Number Generation
(PRNG) algorithms.
Crypto Express5S is an optional feature that was not available in previous generations and is
designed to complement the cryptographic capabilities of the CPACF. It resides in the
Peripheral Component Interconnect Express Generation 2 (PCIe Gen2) I/O drawer and can
be configured in one of the following three ways:
򐂰 Secure IBM Common Cryptographic Architecture (CCA) coprocessor (CEX5C),
– Secure key functions.
– Federal Information Processing Standard (FIPS) 140-2 Security Level 4 certification.
– User-defined extension (UDX) services to implement custom cryptographic functions
and algorithms.
򐂰 Secure IBM Enterprise Public Key Cryptographic Standards (PKCS) #11 (EP11)
coprocessor (CEX5P), providing:
– open, industry-standard cryptographic services following the PKCS #11 specification
v2.20 and more recent amendments. It was designed to extended FIPS and Commom
Criteria evaluations to meet public sector requirements. The new cryptographic
coprocessor mode introduced teh PKCS #11 secure key function.
򐂰 Accelerator (CEX5A), optimized for:
– public and private key cryptographic operations, used with SSL/TLS processing.
For more information about CPACF and Crypto Express4S refer to IBM Redbooks publication
IBM zEnterprise EC12 Technical Guide, SG24-8049, and for more information on how to use
those features at Linux on z Systems, refer to Security for Linux on System z, SG24-7728.
The use of a firewall will be defined by the IT Infrastructure and by the information security
policy of an organization. Making use of guest isolation feature under z/VM and z Systems
architecture makes such a solution as secure as having a firewall executing on every Linux on
Chapter 3. Use case
Draft Document for Review March 12, 2015 2:19 pm
z Systems, but if the information security policy enforces the use of a firewall on any backend
server, including those runing on z Systems environment, that should be implemented.
There are several sophisticated firewall features solutions available for Linux that can filter
and manipulate packets based on complex rules defined by the system administrator. A
preferred practice is to use restrictive firewall policy instead of permissive policy. This will
ensure packets that are explicitly not allowed to flow to the network are dropped, instead of
Some tools helps to automate firewall policy creation. SUSE Enterprise Linux offers a firewall
configuration tool usign YaST that can be used both in graphical mode or text mode. Red Hat
Enterprise Linux offers a firewall configuration tool called system-config-firewall that can also
be used in graphical or text mode. Another option is a tool called Firewall Builder. It is an open
source tool and can be found at:
Firewall Builder can be downloaded and built for SUSE Enterprise Linux Server or Red Hat
Enterprise Linux.
End to End Security with z Systems
Draft Document for Review March 12, 2015 2:19 pm
Back cover
End to End Security with z
Understand z Systems
end-to-end security
Secure z Systems for
z/OS, z/VM and Linux
for z Systems
Understand security
from a use case
This IBM Redpaper Redbooks provides a broad understanding of the
components necessary to secure your IBM z Systems environment.
Here, we provide an end-to-end architectural reference document for a
use case that employs both mobile and analytics. This IBM Redpaper
will be an end to end walk through of security on z Systems from the
systems of record through the systems of engagement. We will discuss
security in terms of transactions - what happens once a transaction
hits the system of engagement and what needs to be in place from that
moment forward.
The audience for this IBM Redpaper is IT architects and those planning
to use z Systems for their mobile and analytics environments.
IBM Redbooks are developed
by the IBM International
Technical Support
Organization. Experts from
IBM, Customers and Partners
from around the world create
timely technical information
based on realistic scenarios.
Specific recommendations
are provided to help you
implement IT solutions more
effectively in your
For more information:
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