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:

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.

German Dridex spam campaign is unfashionably large

VB has analysed a malicious spam campaign targeting German-speaking users with obfuscated Excel malware that would likely download Dridex but that mostly stood out through its size.

Paper: Dexofuzzy: Android malware similarity clustering method using opcode sequence

We publish a paper by researchers from ESTsecurity in South Korea, who describe a fuzzy hashing algorithm for clustering Android malware datasets.

Emotet continues to bypass many email security products

Having returned from a summer hiatus, Emotet is back targeting inboxes and, as seen in the VBSpam test lab, doing a better job than most other malicious campaigns at bypassing email security products.

VB2019 paper: We need to talk - opening a discussion about ethics in infosec

Those working in the field of infosec are often faced with ethical dilemmas that are impossible to avoid. Today, we publish a VB2019 paper by Kaspersky researcher Ivan Kwiatkowski looking at ethics in infosec as well as the recording of Ivan's…

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.