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

twitter.png
fb.png
linkedin.png
hackernews.png
reddit.png

 

Latest posts:

VB2019 paper: Fantastic Information and Where to Find it: A guidebook to open-source OT reconnaissance

A VB2019 paper by FireEye researcher Daniel Kapellmann Zafra explained how open source intelligence (OSINT) can be used to learn crucial details of the inner workings of many a system. Today we publish Daniel's paper and the recording of his…

VB2019 paper: Different ways to cook a crab: GandCrab Ransomware-as-a-Service (RaaS) analysed in depth

Though active for not much longer than a year, GandCrab had been one of the most successful ransomware operations. In a paper presented at VB2019 in London, McAfee researchers John Fokker and Alexandre Mundo looked at the malware code, its evolution…

VB2019 paper: Domestic Kitten: an Iranian surveillance program

At VB2019 in London, Check Point researchers Aseel Kayal and Lotem Finkelstein presented a paper detailing an Iranian operation they named 'Domestic Kitten' that used Android apps for targeted surveillance. Today we publish their paper and the video…

VB2019 video: Discretion in APT: recent APT attack on crypto exchange employees

At VB2019 in London, LINE's HeungSoo Kang explained how cryptocurrency exchanges had been attacked using Firefox zero-days. Today, we publish the video of his presentation.

VB2019 paper: DNS on fire

In a paper presented at VB2019, Cisco Talos researchers Warren Mercer and Paul Rascagneres looked at two recent attacks against DNS infrastructure: DNSpionage and Sea Turtle. Today we publish their paper and the recording of their 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.