Welcome!

Weblogic Authors: Yeshim Deniz, Elizabeth White, Michael Meiner, Michael Bushong, Avi Rosenthal

Blog Feed Post

F5 Friday: Mitigating the THC SSL DoS Threat

The THC #SSL #DoS tool exploits the rapid resource consumption nature of the handshake required to establish a secure session using SSL.

f5friday

A new attack tool was announced this week and continues to follow in the footsteps of resource exhaustion as a means to achieve a DoS against target sites.

Recent trends in attacks show an increasing interest in maximizing effect while minimizing effort. This means a move away from traditional denial of service attacks that focus on overwhelming sites with traffic and toward attacks that focus on rapidly consuming resources, instead. Both have the same ultimate goal: overwhelming infrastructure, whether server or router or <insert infrastructure component of choice>.

The latest SSL-based attack falls into the modern category of denial of service attacks in that it’s not an attempt to overwhelm with traffic, but rather to consume resources on servers such that capacity and the ability to respond to legitimate requests is eliminated.

The blog post announcing the exploit tools explains:

Establishing a secure SSL connection requires 15x more processing power on the server than on the client.

THC-SSL-DOS exploits this asymmetric property by overloading the server and knocking it off the Internet.

This problem affects all SSL implementations today. The vendors are aware of this problem since 2003 and the topic has been widely discussed.

This attack further exploits the SSL secure Renegotiation feature to trigger thousands of renegotiations via single TCP connection.

-- THC SSL DOS Tool Released 

As the blog points out, there is no resolution to this exploit. Common mitigation techniques include the use of an SSL accelerator, i.e. a reverse-proxy capable device with specialized hardware designed to improve the processing capability of SSL and associated cryptographic functions. Modern application delivery controllers like BIG-IP include such hardware by default and make use of its performance and capacity-enhancing abilities to offset the operational costs of supporting SSL-secured communication.

ssl adc mitigationBIG-IP MITIGATION

There are actually several ways in which BIG-IP can mitigate the potential impact of this kind of attack. First and foremost is simply its higher capacity for connections and processing of SSL / RSA operations. BIG-IP can manage myriad more connections – secure or not – than a typical web server and thus it may be, depending on the hardware platform on which BIG-IP is deployed, that the mitigation rests merely on having a BIG-IP in the path of the attack.

In the case that it is not, or if organizations desire a more proactive approach to mitigation, there are two additional options:

1. SSL renegotiation, which is in part the basis for the attack (it’s what allows a relatively few clients to force the server to consume more and more resources), can be disabled in BIG-IP v11 and v10.2.3. This may break some applications and/or clients so this option may want to be left as a “last resort” or the risks carefully weighed before deploying such a configuration.

2. An iRule that drops connections over which a client attempts to renegotiate more than five times in a given 60-second interval can be deployed. As noted by David Holmes and the iRule author, Jason Rahm, “By silently dropping the client connection, the iRule causes the attack tool to stall for long periods of time, fully negating the attack.  There should be no false-positives dropped, either, as there are very few valid use cases for renegotiating more than once a minute.” 

The full details and code for the iRule can be found in the DevCentral article “SSL Renegotiation DOS attack – an iRule Countermeasure

Regardless of the mitigating technique used, BIG-IP can provide the operational security necessary to prevent such consumption-leeching attacks from negatively impacting applications by defeating the attack before it reaches application infrastructure.

Stay safe!


Connect with Lori: Connect with F5:
o_linkedin[1] google  o_rss[1] o_facebook[1] o_twitter[1]   o_facebook[1] o_twitter[1] o_slideshare[1] o_youtube[1]
Related blogs & articles:


Read the original blog entry...

More Stories By Lori MacVittie

Lori MacVittie is responsible for education and evangelism of application services available across F5’s entire product suite. Her role includes authorship of technical materials and participation in a number of community-based forums and industry standards organizations, among other efforts. MacVittie has extensive programming experience as an application architect, as well as network and systems development and administration expertise. Prior to joining F5, MacVittie was an award-winning Senior Technology Editor at Network Computing Magazine, where she conducted product research and evaluation focused on integration with application and network architectures, and authored articles on a variety of topics aimed at IT professionals. Her most recent area of focus included SOA-related products and architectures. She holds a B.S. in Information and Computing Science from the University of Wisconsin at Green Bay, and an M.S. in Computer Science from Nova Southeastern University.

@ThingsExpo Stories
High-velocity engineering teams are applying not only continuous delivery processes, but also lessons in experimentation from established leaders like Amazon, Netflix, and Facebook. These companies have made experimentation a foundation for their release processes, allowing them to try out major feature releases and redesigns within smaller groups before making them broadly available. In his session at 21st Cloud Expo, Brian Lucas, Senior Staff Engineer at Optimizely, will discuss how by using...
In this strange new world where more and more power is drawn from business technology, companies are effectively straddling two paths on the road to innovation and transformation into digital enterprises. The first path is the heritage trail – with “legacy” technology forming the background. Here, extant technologies are transformed by core IT teams to provide more API-driven approaches. Legacy systems can restrict companies that are transitioning into digital enterprises. To truly become a lead...
SYS-CON Events announced today that Yuasa System will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Yuasa System is introducing a multi-purpose endurance testing system for flexible displays, OLED devices, flexible substrates, flat cables, and films in smartphones, wearables, automobiles, and healthcare.
SYS-CON Events announced today that CAST Software will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CAST was founded more than 25 years ago to make the invisible visible. Built around the idea that even the best analytics on the market still leave blind spots for technical teams looking to deliver better software and prevent outages, CAST provides the software intelligence that matter ...
SYS-CON Events announced today that Daiya Industry will exhibit at the Japanese Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Ruby Development Inc. builds new services in short period of time and provides a continuous support of those services based on Ruby on Rails. For more information, please visit https://github.com/RubyDevInc.
As businesses evolve, they need technology that is simple to help them succeed today and flexible enough to help them build for tomorrow. Chrome is fit for the workplace of the future — providing a secure, consistent user experience across a range of devices that can be used anywhere. In her session at 21st Cloud Expo, Vidya Nagarajan, a Senior Product Manager at Google, will take a look at various options as to how ChromeOS can be leveraged to interact with people on the devices, and formats th...
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
SYS-CON Events announced today that Taica will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Taica manufacturers Alpha-GEL brand silicone components and materials, which maintain outstanding performance over a wide temperature range -40C to +200C. For more information, visit http://www.taica.co.jp/english/.
Organizations do not need a Big Data strategy; they need a business strategy that incorporates Big Data. Most organizations lack a road map for using Big Data to optimize key business processes, deliver a differentiated customer experience, or uncover new business opportunities. They do not understand what’s possible with respect to integrating Big Data into the business model.
Enterprises have taken advantage of IoT to achieve important revenue and cost advantages. What is less apparent is how incumbent enterprises operating at scale have, following success with IoT, built analytic, operations management and software development capabilities – ranging from autonomous vehicles to manageable robotics installations. They have embraced these capabilities as if they were Silicon Valley startups. As a result, many firms employ new business models that place enormous impor...
Amazon is pursuing new markets and disrupting industries at an incredible pace. Almost every industry seems to be in its crosshairs. Companies and industries that once thought they were safe are now worried about being “Amazoned.”. The new watch word should be “Be afraid. Be very afraid.” In his session 21st Cloud Expo, Chris Kocher, a co-founder of Grey Heron, will address questions such as: What new areas is Amazon disrupting? How are they doing this? Where are they likely to go? What are th...
SYS-CON Events announced today that MIRAI Inc. will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MIRAI Inc. are IT consultants from the public sector whose mission is to solve social issues by technology and innovation and to create a meaningful future for people.
SYS-CON Events announced today that Dasher Technologies will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Dasher Technologies, Inc. ® is a premier IT solution provider that delivers expert technical resources along with trusted account executives to architect and deliver complete IT solutions and services to help our clients execute their goals, plans and objectives. Since 1999, we'v...
SYS-CON Events announced today that NetApp has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. NetApp is the data authority for hybrid cloud. NetApp provides a full range of hybrid cloud data services that simplify management of applications and data across cloud and on-premises environments to accelerate digital transformation. Together with their partners, NetApp emp...
SYS-CON Events announced today that IBM has been named “Diamond Sponsor” of SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California.
SYS-CON Events announced today that TidalScale, a leading provider of systems and services, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. TidalScale has been involved in shaping the computing landscape. They've designed, developed and deployed some of the most important and successful systems and services in the history of the computing industry - internet, Ethernet, operating s...
Infoblox delivers Actionable Network Intelligence to enterprise, government, and service provider customers around the world. They are the industry leader in DNS, DHCP, and IP address management, the category known as DDI. We empower thousands of organizations to control and secure their networks from the core-enabling them to increase efficiency and visibility, improve customer service, and meet compliance requirements.
SYS-CON Events announced today that IBM has been named “Diamond Sponsor” of SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California.
Join IBM November 1 at 21st Cloud Expo at the Santa Clara Convention Center in Santa Clara, CA, and learn how IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Cognitive analysis impacts today’s systems with unparalleled ability that were previously available only to manned, back-end operations. Thanks to cloud processing, IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Imagine a robot vacuum that becomes your personal assistant tha...
In a recent survey, Sumo Logic surveyed 1,500 customers who employ cloud services such as Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP). According to the survey, a quarter of the respondents have already deployed Docker containers and nearly as many (23 percent) are employing the AWS Lambda serverless computing framework. It’s clear: serverless is here to stay. The adoption does come with some needed changes, within both application development and operations. Tha...