The Top 10 DDoS Attack Trends

The Top 10 DDoS Attack Trends
WHITE PAPER
The Top 10 DDoS Attack Trends
Discover the Latest DDoS Attacks and Their
Implications
Introduction
The volume, size and sophistication of distributed denial of service (DDoS)
attacks are increasing rapidly, which makes protecting against these threats
an even bigger priority for all enterprises. In order to better prepare for DDoS
attacks, it is important to understand how they work and examine some of the
most widely-used tactics.
What Are DDoS Attacks?
A DDoS attack may sound complicated, but it is actually quite easy to
understand. A common approach is to “swarm” a target server with thousands
of communication requests originating from multiple machines. In this way the
server is completely overwhelmed and cannot respond anymore to legitimate
user requests. Another approach is to obstruct the network connections
between users and the target server, thus blocking all communication between
the two – much like clogging a pipe so that no water can flow through.
Attacking machines are often geographically-distributed and use many different
internet connections, thereby making it very difficult to control the attacks. This
can have extremely negative consequences for businesses, especially those that
rely heavily on its website; E-commerce or SaaS-based businesses come to mind.
The Open Systems Interconnection (OSI) model defines seven conceptual layers
in a communications network. DDoS attacks mainly exploit three of these layers:
network (layer 3), transport (layer 4), and application (layer 7).
Network (Layer 3/4) DDoS Attacks: The majority of DDoS attacks target the
network and transport layers. Such attacks occur when the amount of data
packets and other traffic overloads a network or server and consumes all of its
available resources.
Application (Layer 7) DDoS Attacks: Breach or vulnerability in a web
application. By exploiting it, the perpetrators overwhelm the server or database
powering a web application, bringing it to its knees. Such attacks mimic
legitimate user traffic, making them harder to detect.
Why You Need To Read This White Paper
This white paper presents the top ten current methods and trends in DDoS attacks based
on real-world observation and data. It provides insight regarding:
▪▪ Volumetric attacks
▪▪ SYN flood attacks
▪▪ NTP amplification attacks
▪▪ ’Hit and Run’ attacks
▪▪ Browser based bot attacks
▪▪ Multi target DDoS botnets
▪▪ Spoofed user-agents
▪▪ Multi-vector attacks
▪▪ Attacks from mobile devices
▪▪ Geographic locations for attack origination
This white paper concludes with an actionable plan and solutions you can implement to
prevent these types of attacks.
2
Large Scale, Volumetric Attacks Are Getting Bigger
What Are Volumetric Attacks?
Latest Trends
▪▪ There was a 350%
increase in large-scale
volumetric DDoS attacks
in the first half of 2014
when compared to the
previous year.
▪▪ Attacks of 20 Gbps and
above now account for
more than 1/3rd of all
network DDoS events.
▪▪ DDoS attacks of over
100 Gbps increased to
an overwhelming 100+
events in the first half of
2014 alone.
Volumetric attacks flood a target network with data packets that completely saturate the
available network bandwidth. These attacks cause very high volumes of traffic congestion,
overloading the targeted network or server and causing extensive service disruption for
legitimate users trying to gain access.
Volumetric attacks are getting larger, more sophisticated, and are lasting for a longer
duration. They can bring any business server down within a few minutes. These networklevel (layers 3 and 4) attacks are designed to overwhelm a server’s internet link, network
resources, and appliances that are not able to absorb the increased volumes.
Application (Layer 7) DDoS Attack Overview
Implications
As volumetric DDoS attacks continue to evolve, organizations will need ever more network
resources to battle them. Even companies with significant amounts of internet connectivity
and bandwidth could see their capacity exhausted by these attacks and buying significant
additional bandwidth can be very expensive.
3
Combo SYN Flood Attacks Are Most Common
What Are Combo SYN Flood Attacks?
Latest Trends
▪▪ Combo SYN flood
attacks account for 75%
of all large scale (above
20Gbps) network DDoS
events.
▪▪ Half of all network DDoS
attacks are SYN flood
attacks.
▪▪ Large SYN flood are the
single most commonly
used attack vector,
accounting for 26% of all
network DDoS events.
In the TCP connection sequence (the “three-way handshake”), the requester first sends a
SYN message to initiate a TCP connection with a host. The server responds with a SYN-ACK
message, followed by receipt confirmation of the ACK message by the requester. This
opens the network connection.
In a SYN flood attack, the requester sends multiple SYN messages to the targeted server,
but does not transmit any confirmation ACK messages. The requester can also dispatch
spoofed SYN messages, causing the server to send SYN-ACK responses to a falsified IP
address. Of course, it never responds because it never originated the SYN messages.
The SYN flood binds server resources until no new connections can be made, ultimately
resulting in denial of service.
A combo SYN flood comprises two types of SYN attacks – one uses regular SYN packets,
the other large SYN packets above 250 bytes. Both attacks are executed at the same time;
the regular SYN packets exhaust server resources (e.g., CPU), while the larger packets cause
network saturation.
Multi-Vector Attacks Facilitate Hyper Growth
Implications
A combo SYN flood attack remains the ”weapon of choice” for perpetrators. These
attacks quickly consume resources of a target server, or of intermediate communications
equipment (e.g., firewalls and load balancers), making them difficult to combat using
traditional DDoS mitigation strategies.
4
NTP Amplification Attacks Are Significantly
Increasing
What Are NTP Amplification Attacks?
Latest Trends
▪▪ 400 Gbps NTP
amplification attack in
February 2014 is the
largest DDoS attack ever
reported.
▪▪ In Q1 2014, the number
of NTP amplification
attacks increased by
an astonishing 372%
compared to Q4 2013.
▪▪ NTP amplification is now
the primary attack vector
and is starting to surpass
SYN flood attacks.
Computers use the Network Time Protocol (NTP) to synchronize their clocks over the
internet. NTP amplification attacks exploit a feature on NTP servers; called MONLIST, it
returns a list of the last 600 IP addresses that communicated with the server. Attackers
send out MONLIST requests to NTP servers using a target server’s spoofed IP address.
Thus the NTP server response is much larger than the original request. By using numerous
vulnerable NTP servers, attackers are quickly able to compromise the target server, it being
overwhelmed with multiple data packets.
In part, NTP amplification attacks can be massive because the underlying UDP protocol
does not require any handshaking.
On The Rise - NTP Amplification Attacks
Implications
There are more than 400,000 NTP servers around the world that can potentially be used
in an NTP amplification attack. Some are capable of amplification factors up to 700 times,
which could result in a huge blow to internet traffic.
5
“Hit and Run” Attacks are Ever Persistent
What Are “Hit and Run” Attacks?
Latest Trends
▪▪ Hit and run attacks
typically last 20 – 60
minutes in duration.
▪▪ After causing some
collateral damage to a
target server, hit and run
attacks usually occur
again after another 12 –
48 hours.
▪▪ Traditional DDoS
prevention solutions, such
as GRE tunneling and DNS
rerouting, have become
ineffective in dealing with
these types of attacks.
As their name suggests, hit and run attacks consist of short packet bursts at random
intervals over a long period of time. What makes these threats different from other DDoS
attacks is that they can last for days or even weeks. Also, unlike other attacks, they are not
continuous and are designed to specifically exploit slow-reacting anti-DDoS solutions.
Despite the sophistication of other kinds of DDoS threats, hit and run attacks continue to
be popular because of their low cost and ease of deployment.
Hit and Run Attacks
Implications
Hit and run attacks wreak havoc with “on-demand” DDoS mitigation solutions that need to
be manually engaged/disengaged with every burst. Such attacks are changing the face of
the anti-DDoS industry, pushing it toward “always on” integrated solutions. Any mitigation
that takes more than a few seconds is simply unacceptable.
6
The Sophistication of Browser-Based Bots
What Are Browser Based Bots?
Latest Trends
▪▪ Browser-based DDoS
bots are becoming more
sophisticated and are
now able to bypass both
JavaScript and cookie
challenges – the two
most common methods
used for bot filtering.
▪▪ 30% of all DDoS bots
encountered in 2014 were
able to accept and store
cookies, while 0.8% of
them could also execute
JavaScript.
Browser-based bots consist of malicious software code segments running inside a web
browser. The bots run during a legitimate web browsing session; once the browser is
closed, the bot session automatically terminates. Browser-based bots are surreptitiously
installed on unsuspecting users’ computers upon visiting a malicious website. Multiple
bots can then simultaneously launch an attack against a targeted server from
compromised machines.
Some DDoS bot types imitate browser behavior, such as support for cookies, in order to
evade anti-DDoS defenses. DDoS bot attacks target the application layer and are extremely
dangerous because they don’t require high volumes to succeed. It only takes 50 – 100
targeted requests per second to bring down a mid-size server. Bot attacks are hard to
detect and often revealed only after the damage has been done.
Bots are Evolving Developing Immunity to Cookie and JavaScript Challenges
DDoS Bots’ Capabilities
Primitive Bots
Accept Cookies
Can Execute JavaScript
Implications
Identifying layer 7 attacks requires an understanding of the underlying application. It also
requires proper differentiation between malicious bot traffic, regular bot traffic (such as
search engine bots), and human traffic. The ability to analyze incoming traffic and assign
a contextual risk score based on the visitor’s identity, behavior, and reputation is an
additional factor.
7
Spoofed User-Agents Used In Most Bot Sessions
What Are Spoofed User Agents?
Latest Trends
▪▪ The top five spoofed
agents shown in the list
below account for 85%
of all malicious DDoS bot
sessions.
▪▪ Bot traffic accounts for
62% of all website traffic,
half of which consists of
search engines and other
good bots – the other half
comprising malicious bots.
Good bots, such as “Googlebots” are critical to ensuring that websites are properly indexed
by search engines. It is therefore important not to accidentally block them.
Spoofing user agents is a frequently-used attack technique. Here the DDoS bots
masquerade as “good” bots from reputable sources such as Google or Yahoo, in order to
evade detection. Using this method, the bots are able to pass through low-level filters and
proceed to wreak havoc on target servers.
Common Spoofed User-Agents
Top 10 Spoofed User-Agents Used by DDoS Bots
33.0 % Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)
16.0 % Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
13.0 % Mozilla/5.0+(compatible;+Baiduspider/2.0;++http://www.baidu.com/search/spider.html)
11.7 % Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
10.4 % Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; SV1)
6.8% Mozilla/4.0 (compatible; MSIE 7.00; Windows NT 5.0; MyIE 3.01)
6.5% Mozilla/4.0 (compatible; MSIE 8.00; Windows NT 5.0; MyIE 3.01)
1.6% Mozilla/5.0 (X11; U; Linux i686; en-US; re:1.4.0) Gecko/20080808 Firefox/8.0
0.2% Mozilla/4.0 (Windows; U; Windows NT 5.1; zh-TW; rv:1.9.0.11)
0.1% Mozilla/4.0 (compatible; MSIE 6.0; Windows 5.1)
Implications
The list is dominated by malicious bots masquerading as search engine bots. From a
mitigation point of view, they represent the easiest of all application layer challenges, due
to the highly-predictable behavior patterns of legitimate search engine bots, as well as their
predetermined points of origin.
8
30% of DDoS Botnets Attack 50+ Targets
Per Month
What Are Shared Botnets?
Latest Trends
▪▪ DDoS botnets are being
reused to attack multiple
targets. On average, 30%
of botnets attack more
than 50 targets each
month.
▪▪ 1.2% of botnets attack
over 200 targets each
month; both of these
numbers are increasing.
▪▪ Marketplaces are available
across the internet,
increasingly selling access
to sophisticated botnets
for very low prices.
A botnet is a group of compromised computers on the internet, taken over by malware.
Machine owners are usually unaware of malicious software infiltration, thereby allowing
attackers to control their “zombie” machines remotely and launch DDoS attacks. In addition
to personal computers, botnets can also include hijacked hosting environments and
various internetconnected devices (e.g., CCTV cameras which often have easy-to-guess
default passwords).
Botnets are frequently shared between hackers or rented by one attacker from another.
They can have multiple owners and use the same compromised machines for launching
attacks against different targets. Shared botnets are available for hire on the internet and
can be easily launched by non-technical users.
29% of Botnets Attack More than 50 Targets a Month
Number of Monthly Targets
Per Botnet
Less than 20
More than 20
More than 50
More than 100
More than 200
Implications
Shared botnet attacks continue to significantly increase, because they can be accessed
cheaply and easily utilized without any technical knowledge. DDoS mitigation systems
must be proactive and use reputation-based security methods to anticipate user intentions
(and be able to red flag them as necessary).
9
Over 80% of Attacks Use Multi-Vector Approach
What Are Multi-Vector Attacks?
Latest Trends
▪▪ 81% of DDoS attacks
employed at least two
types of vectors.
▪▪ 40% of DDoS attacks used
three or more different
vectors at the same time.
▪▪ In order to mount
large-scale attacks, more
than 75% of multivector attacks used a
combination of SYN
methods (such as using
regular SYN packets and
much larger SYN packets
greater than 250 bytes).
Traditionally, DDoS attack campaigns used a single attack type, or vector. However, there is
a rise in DDoS attacks using multiple vectors to disable a network or server(s). Called multivector attacks, they consist of some combination of the following: (1) Volumetric attacks; (2)
State-exhaustion attacks; and (3) Application layer attacks.
The multi-vector approach is very appealing to an attacker, since the tactic can create the
most collateral damage to a business or organization. These attacks increase the chance
of success by targeting several different network resources, or using one attack vector as a
decoy while another, more powerful vector is used as the main weapon.
Over 81% of Attacks Are Multi-Vector Threats
Network DDoS Attacks: Distribution by Number of Vectors
Implications
The fact that multi-vector attacks are so prevalent now indicates the level of familiarity
attackers have developed with website security and DDoS protection products. These
attacks can be extremely difficult to mitigate because they require a multi-layered approach
across the entire data center/enterprise and a highly-skilled IT team to combat them.
10
Attacks from Mobile Devices Are Increasing
What Are Mobile Device Attacks?
Latest Trends
▪▪ More powerful
mobile devices and
downloadable attack
apps (especially on
Android-based devices)
have made it much easier
for attacks to be launched
from them.
▪▪ New tools, such as Low
Orbit Ion Cannon (LOIC),
are freely available and let
individuals intentionally
“opt in” to participate in
attacks.
As markets have become saturated with mobile devices, the number of attacks has
dramatically increased. With cellular networks providing more internet bandwidth and
faster connectivity, it has become easier for mobile devices to be hijacked and unwittingly
used to launch DDoS attacks. Mobile phones and tablets are not impervious to malware,
and can be easily infected without the knowledge of their owners. They can then be used
to download malicious software and launch DDoS attacks together with other, similarlyhijacked mobile devices, all secretly-controlled by the attacker.
Mobile devices have weaker security protection compared to PCs. Most users do not install
any type of anti-virus application on them. Owners also download apps more freely on
mobile devices without much thought regarding security. This makes it easier for malicious
apps to compromise these devices.
Implications
With mobile devices becoming more ubiquitous and powerful, the number of attacks from
mobile devices will likely rise sharply. There is an additional layer of complexity in mitigating
attacks from mobile devices; cellular networks cannot use traditional firewalls to block
source IP addresses since they would also affect legitimate traffic.
11
52% of Attacks Originate From Only Ten Countries
In Which Geolocations Do DDoS Attacks Originate?
Latest Trends
▪▪ The top five spoofed
agents shown in the list
below account for 85%
of all malicious DDoS bot
sessions.
▪▪ Bot traffic accounts for
62% of all website traffic,
half of which consists of
search engines and other
good bots – the other
half comprising malicious
bots.
DDoS attacks are frequently routed through hijacked hosting environments or internet
connected devices in regions having an insecure infrastructure. The attacks may originate
in another country, but are then amplified through other environments. IT infrastructures in
these countries tend to have weaker security measures in place, which is why computing
resources located therein are used more frequently to commit attacks.
Top Attack Originating Countries
Implications
Attacks will likely continue to increase from these regions as IT infrastructures and the
number of internet-connected devices therein is increasing at a much larger rate than
other locales. The implementation of stronger regulation and security controls within
these regions could significantly reduce the number of attacks originating from within
their borders.
12
Conclusion
DDoS attacks are constantly evolving in terms of their technology, sophistication level, and
tactics. New attack tools are being regularly released, and – what is particularly alarming –
some of them are so user-friendly they require little-to-no technical knowledge to initiate
attacks. Highly-disruptive botnets, powered by thousands of servers, are also now available
for rent, and at very low prices. As a consequence, the number, magnitude, and disruption
level of DDoS attacks is expected to scale to new levels.
Traditional anti-DDoS products are no longer sufficient to meet these challenges. These
consist of appliance-based solutions having bandwidth limitations; “on demand” mitigation
requiring manual activation; rate-limiting solutions that are ineffective against IP spoofing;
and delay/splash screens that impair the user experience.
Effective DDoS Mitigation Solution Requirements
To protect against all current and future DDoS attacks, an all-encompassing mitigation
solution requires the following:
▪▪ Cloud-based DDoS mitigation
▪▪ A high-capacity network
▪▪ Automatic/instant detection and mitigation
▪▪ Visitor identification, risk analysis, and progressive challenges
▪▪ Minimal disruption to website user experience
▪▪ Always-on DDoS protection
Imperva Incapsula – Protecting You Against All the Latest DDoS
Attack Trends
Incapsula DDoS protection solution exceeds all of the above requirements. Being a cloudbased, “always-on” solution, it protects against attacks on any level, be they network (layer
3), protocol (layer 4), or application (layer 7).
Incapsula offers a unique capability set specifically designed to address the latest trends
in the DDoS threat landscape. Being a cloud-based service running over a high-capacity
global network, it scales on demand to counter multi-gigabyte, network layer 3 DDoS
attacks. Advanced traffic analysis algorithms block malicious traffic at the protocol
layer (4), and an enterprise-grade web application firewall employs user classification,
granular mitigation rules, and progressive challenges to thwart sophisticated layer 7
application attacks.
Incapsula CDN evenly distributes traffic between data centers while simultaneously
accelerating legitimate traffic to decrease latency. Each data center holds several
interconnected, high-powered scrubbing servers, used for real-time DDoS traffic profiling
and blocking.
13
With Imperva Incapsula DDoS protection solution you get:
▪▪ An “always-on” service having instant detection and mitigation.
▪▪ Cloud-based platform that is swiftly updated to address the latest attack types.
▪▪ Powerful network of globally-positioned data centers to block the largest of attacks.
▪▪ Blanket DDoS protection for all types of services (UDP/TCP, SMTP, HTTP, FTP, SSH, VoIP, etc.)
▪▪ Backed by a 24 × 7 security team and a 99.999% uptime SLA
About Imperva
Imperva, pioneering the third pillar of enterprise security, fills the gaps in endpoint and network security by directly
protecting high-value applications and data assets in physical and virtual data centers. With an integrated security
platform built specifically for modern threats, Imperva data center security provides the visibility and control needed to
neutralize attack, theft, and fraud from inside and outside the organization, mitigate risk, and streamline compliance. Over
3,500 customers in more than 90 countries rely on our SecureSphere platform to safeguard their business. Imperva is
headquartered in Redwood Shores, California.
Learn more at www.imperva.com.
www.imperva.com
© Copyright 2015, Imperva
All rights reserved. Imperva and SecureSphere are registered trademarks of Imperva.
All other brand or product names are trademarks or registered trademarks of their respective holders. #WP-TOP10-DDOS-ATTACK-TRENDS-0115rev2
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