Paper: The Hulk

Posted by   Virus Bulletin on   Oct 8, 2014

Raul Alvarez studies cavity file infector.

Most file infectors increase the length of the infected file, as the malicious code is added as a new section of the host file, or to the last section of that file. 'Cavity' file infectors are different though: they infect files without increasing their size.

Today, we publish a paper by Raul Alvarez, a researcher for Fortinet, in which he studies Win32/Huhk, a virus that implements cavity file infection.

In the paper, Raul explains what happens when an infected file is run, as well as how other files are being infected. Huhk is polymorphic in nature, something which is achieved through a simple XOR operation with a one-byte key.

Of course, the virus needs to find a way to hide in the host file without affecting the latter's ability to run. To this end, Huhk looks for continuous memory locations filled with zeros. If the total size of such locations is greater than 7,005 bytes, it is able to infect the file.

You can read the paper here in HTML format or here as a PDF.

If you like this paper, you will probably like two other papers by Raul we published recently: Bird's Nest (on Neshta) and API-EPO (on W32/Daum).

Posted on 08 October 2014 by Martijn Grooten

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

 

Latest posts:

VBSpam tests to be executed under the AMTSO framework

VB is excited to announce that, starting from the Q3 test, all VBSpam tests of email security products will be executed under the AMTSO framework.

In memoriam: Prof. Ross Anderson

We were very sorry to learn of the passing of Professor Ross Anderson a few days ago.

In memoriam: Dr Alan Solomon

We were very sorry to learn of the passing of industry pioneer Dr Alan Solomon earlier this week.

New paper: Nexus Android banking botnet – compromising C&C panels and dissecting mobile AppInjects

In a new paper, researchers Aditya K Sood and Rohit Bansal provide details of a security vulnerability in the Nexus Android botnet C&C panel that was exploited in order to gather threat intelligence, and present a model of mobile AppInjects.

New paper: Collector-stealer: a Russian origin credential and information extractor

In a new paper, F5 researchers Aditya K Sood and Rohit Chaturvedi present a 360 analysis of Collector-stealer, a Russian-origin credential and information extractor.

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.