Tor exit node found to turn downloaded binaries into malware

Posted by   Virus Bulletin on   Oct 24, 2014

Tor provides anonymity, not security, hence using HTTPS is essential.

A security researcher has discovered a Tor exit node that was modifying binaries downloaded through it on the fly.

The researcher, Josh Pitts of Leviathan Security, has previously shown how easy it is to modify binaries downloaded over HTTP in transit, thus turning them into malware. He emphasised the importance of using HTTPS when downloading executables from a remote server.

Of course, there are other ways to protect the integrity of downloaded binaries, such as digital signatures. But whether those are verified, and what is done upon finding an invalid signature, is up to the entity executing the binary, which could be an end-user, but also Windows Update.

In a recent presentation at DerbyCon, Josh concluded by saying he worried that this technique of 'patching' binaries "might already be in use".

It now turns out he was right: scanning the exit nodes of the Tor anonymity network, Josh found one exit node based in Russia that was patching all (uncompressed) Windows executables downloaded through it by adding malware.

This is a good reminder that Tor provides anonymity, but not security. Those operating an exit node have a privileged network position, similar to that of someone running a wireless network in a coffee shop, with the difference that those running the network cannot determine the IP address of the computer making the requests.

For many attacks, such as turning downloaded binaries into malware, this difference is not an issue. Moreover, by looking at the requests you make, an adversary might be able to determine who you are. Hence using plain HTTP over Tor is usually a very bad idea.

Even when using HTTPS one should be cautious. The privileged network position could allow an exit node operator to perform the POODLE attack against SSL 3.0.

The Tor Project has now added the malicious exit node to its blacklist, preventing Tor users from using it. Tor's Roger Dingledine warns that it is best "to have applications not blindly trust unauthenticated bits they get from the Internet".

Posted on 24 October 2014 by Martijn Grooten



Latest posts:

VB2019 paper: APT cases exploiting vulnerabilities in region-specific software

At VB2019, JPCERT/CC's Shusei Tomonaga and Tomoaki Tani presented a paper on attacks that exploit vulnerabilities in software used only in Japan, using malware that is unique to Japan. Today we publish both their paper and the recording of their…

New paper: Detection of vulnerabilities in web applications by validating parameter integrity and data flow graphs

In a follow-up to a paper presented at VB2019, Prismo Systems researchers Abhishek Singh and Ramesh Mani detail algorithms that can be used to detect SQL injection in stored procedures, persistent cross-site scripting (XSS), and server‑side request…

VB2020 programme announced

VB is pleased to reveal the details of an interesting and diverse programme for VB2020, the 30th Virus Bulletin International Conference.

VB2019 paper: Cyber espionage in the Middle East: unravelling OSX.WindTail

At VB2019 in London, Jamf's Patrick Wardle analysed the WindTail macOS malware used by the WindShift APT group, active in the Middle East. Today we publish both Patrick's paper and the recording of his presentation.

VB2019 paper: 2,000 reactions to a malware attack – accidental study

At VB2019 cybercrime journalist and researcher Adam Haertlé presented an analysis of almost 2000 unsolicited responses sent by victims of a malicious email campaign. Today we publish both his paper and the recording of his presentation.

We have placed cookies on your device in order to improve the functionality of this site, as outlined in our cookies policy. However, you may delete and block all cookies from this site and your use of the site will be unaffected. By continuing to browse this site, you are agreeing to Virus Bulletin's use of data as outlined in our privacy policy.