Hacker group releases attack tool for SSL

Connect with state & local government leaders
 

Connecting state and local government leaders

The German group The Hacker's Choice says it released the tool to force vendors to fix vulnerabilities that have been known for years, but SSL v.3's co-author disagrees with the group's assessment.

A German hacker group has released a tool for launching denial-of-service attacks against Secure Sockets Layer servers used to secure online transactions, exploiting vulnerabilities that have been known for years.

The group, The Hacker’s Choice said in a press release issued Oct. 24 that the tool is an effort to force the industry to correct flaws in the SSL protocol.

“We are hoping that the fishy security in SSL does not go unnoticed,” the group said in the release. “The industry should step in to fix the problem so that citizens are safe and secure again.”


Related stories:

Team cracks chips used in military, aerospace systems

Cracks in encryption security for embedded chips not fatal, company says


Paul Kocher, co-author of SSL v. 3.0, disagreed with the hackers’ assessment.

“This isn’t a vulnerability in the protocol,” said Kocher, president of Cryptography Research Inc. Instead, it's a question of how much computational effort is required to do the cryptography, and the attack threat probably can be defended against with proper configuration of servers, he said. “I wouldn’t expect there to be any protocol changes as a result of this.”

SSL is a commonly used tool to secure network connections using public-key cryptography (and it puts "HTTPS" into the URL). The group described SSL security as out of date and needlessly complex. The THC SSL DOS tool leverages the disproportionate amount of processing power required for a server to establish a secure SSL connection and exploits the secure renegotiation feature of SSL servers by triggering thousands of renegotiations with a single TCP connection.

The group said that because of the asymmetric computing requirements, a single laptop with a DSL connection can take down an average SSL server. Taking down a larger server farm using SSL load balancing would take 20 laptops.

“All in all, superb results,” the group said in the release.

The Hacker’s Choice describes itself as a group of computer enthusiasts and security researchers dating back to 1995.

“THC is not an underground hacking club for illegal activities,” the group says. “Our team consists of open-minded, friendly people concerned with real problems. If you prefer doing your stuff alone in the dark or seek to conflict with laws, THC is not your group.”

The group has released a number of software tools, including an IPv6 attack toolkit for scanning and exploiting inherent vulnerabilities in the new version of the Internet Protocols, vulnerability scanners, password crackers and tools to unlock cell phones, as well as T-shirts.

The group described the DOS tool as a proof of concept that was released publicly after it they realized it had been leaked several months ago. It uses a technique called resource exhaustion, rather than flooding, to overwhelm a server. Flooding typically requires a number of attacking computers in a distributed attack to knock a server offline with the sheer volume of requests. Resource exhaustion relies on the fact that establishing a secure SSL session requires 15 times more processing power on the server side than on the client.

This disparity can allow a single computer with limited bandwidth to swamp a server. The effect is amplified by exploiting secure renegotiation, which further consumes capacity by forcing the server to repeatedly renegotiate the exchange of cryptographic keys. The feature is enabled by default on most servers, although it rarely is used, THC said.

“Renegotiating key material is a stupid idea from a cryptography standpoint,” the group said in its release. “If you are not happy with the key material negotiated at the start of the session, then the session should be re-established and not renegotiated.”

The group said there are no short-term fixes to the vulnerabilities but advised that disabling SSL renegotiation or using an SSL accelerator to offload some of the processing from the server could help, although either countermeasure can be circumvented by modifying the attack tool.

Kocher said the renegotiation feature is a relic of older cryptographic export control rules that could require use of different strength keys for connections with different countries that probably are seldom used now. He said that turning off renogiation and using SSL acceleration should be an adequate protection against denial-of-service attacks, and is more efficient than chaning the protocols and making them more difficult to use.

“There certainly are a lot of badly configured servers out there,” he said, and the release of the attack tool could spur them to correct problems. But most bit users of SSL should already be prepared to deal with DOS attacks, he said.

 

X
This website uses cookies to enhance user experience and to analyze performance and traffic on our website. We also share information about your use of our site with our social media, advertising and analytics partners. Learn More / Do Not Sell My Personal Information
Accept Cookies
X
Cookie Preferences Cookie List

Do Not Sell My Personal Information

When you visit our website, we store cookies on your browser to collect information. The information collected might relate to you, your preferences or your device, and is mostly used to make the site work as you expect it to and to provide a more personalized web experience. However, you can choose not to allow certain types of cookies, which may impact your experience of the site and the services we are able to offer. Click on the different category headings to find out more and change our default settings according to your preference. You cannot opt-out of our First Party Strictly Necessary Cookies as they are deployed in order to ensure the proper functioning of our website (such as prompting the cookie banner and remembering your settings, to log into your account, to redirect you when you log out, etc.). For more information about the First and Third Party Cookies used please follow this link.

Allow All Cookies

Manage Consent Preferences

Strictly Necessary Cookies - Always Active

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data, Targeting & Social Media Cookies

Under the California Consumer Privacy Act, you have the right to opt-out of the sale of your personal information to third parties. These cookies collect information for analytics and to personalize your experience with targeted ads. You may exercise your right to opt out of the sale of personal information by using this toggle switch. If you opt out we will not be able to offer you personalised ads and will not hand over your personal information to any third parties. Additionally, you may contact our legal department for further clarification about your rights as a California consumer by using this Exercise My Rights link

If you have enabled privacy controls on your browser (such as a plugin), we have to take that as a valid request to opt-out. Therefore we would not be able to track your activity through the web. This may affect our ability to personalize ads according to your preferences.

Targeting cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising.

Social media cookies are set by a range of social media services that we have added to the site to enable you to share our content with your friends and networks. They are capable of tracking your browser across other sites and building up a profile of your interests. This may impact the content and messages you see on other websites you visit. If you do not allow these cookies you may not be able to use or see these sharing tools.

If you want to opt out of all of our lead reports and lists, please submit a privacy request at our Do Not Sell page.

Save Settings
Cookie Preferences Cookie List

Cookie List

A cookie is a small piece of data (text file) that a website – when visited by a user – asks your browser to store on your device in order to remember information about you, such as your language preference or login information. Those cookies are set by us and called first-party cookies. We also use third-party cookies – which are cookies from a domain different than the domain of the website you are visiting – for our advertising and marketing efforts. More specifically, we use cookies and other tracking technologies for the following purposes:

Strictly Necessary Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Functional Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Performance Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Social Media Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Targeting Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.