Paper: Prosecting the Citadel botnet - revealing the dominance of the Zeus descendent: part two

Posted by   Virus Bulletin on   Sep 11, 2014

Aditya K. Sood and Rohit Bansal study the malware's behaviour when ran on a physical machine.

Last week, we published the first part of the paper 'Prosecting the Citadel botnet - revealing the dominance of the Zeus descendent'. In it, researchers Aditya K. Sood and Rohit Bansal looked at the design and implementation of the infamous Citadel botnet, as well as the admin panel used by Citadel's botheders.

Today, we publish the second part of the paper. In it, Aditya and Rohit analyse a new sample of the malware. Obtaining suh as sample wasn't trivial, as the malware targets only certain countries and regions and they had to try various VPN servers in different locations before they were successful.

Then they allowed the malware to install, initially in a virtual environment. However, this failed: rather than connecting to the real command and control server, Citadel made various bogus DNS requests in an attempt to confuse researchers. This behaviour is common in today's malware; we wrote about it in much detail a few weeks ago, when we previewed James Wyke's VB2014 paper.

  Bogus DNS traffic sent when the botnet detects it is running inside a virtual environment.

Although far more cumbersome, there is always the option to run the malware on a physical machine. Once they had done that, the researchers were able to capture the traffic the malware made to its C&C server to download the configuration file, after first making sure it was allowed to do so.

In a move which is not uncommon for modern malware, Citadel contains a separate dropper that removes itself once the actual malware is installed. The malware creates an entry in the registry to maintain persistence following reboots. It performs API hooking to conduct its primary function: man-in-the-browser attacks to steal and alter HTTP requests and responses.

The paper concludes with a signature for the Snort IDS, that should help administrators detect Citadel infections on their network, based on the C&C traffic.

The second part of the paper can be viewed here, while a PDF of the full paper can be downloaded here.

Posted on 11 September 2014 by Martijn Grooten

twitter.png
fb.png
linkedin.png
googleplus.png
reddit.png

 

Latest posts:

Necurs pump-and-dump spam campaign pushes obscure cryptocurrency

A Necurs pump-and-dump spam campaign pushing the lesser known Swisscoin botnet is mostly background noise for the Internet.

Alleged author of creepy FruitFly macOS malware arrested

A 28-year old man from Ohio has been arrested on suspicion of having created the mysterious FruitFly malware that targeted macOS and used it to spy on its victims.

The threat and security product landscape in 2017

At the start of the new year, Virus Bulletin looks back at the threats seen in the 2017 and at the security products that are available to help mitigate them.

Spamhaus report shows many botnet controllers look a lot like legitimate servers

Spamhaus's annual report on botnet activity shows that botherders tend to use popular, legitimate hosting providers, domain registrars and top-level domains when setting up command-and-control servers.

Tips on researching tech support scams

As tech support scammers continue to target the computer illiterate through cold calling, VB's Martijn Grooten uses his own experience to share some advice on how to investigate such scams.