Summary

A new variant of Doomjuice worm was found on 11th of February. This one also attacks against www.microsoft.com.

F-Secure monitors the ongoing Mydoom-related attacks in our Weblog: http://www.f-secure.com/weblog/

Additional Details

Doomjuice.B is similar to to the original Doomjuice.A. This variant tries to improve the Distributed Denial-of-Service attack on www.microsoft.com. The size of this variant is smaller, as Doomjuice.B does not contain or drop the source code of Mydoom.A.

System Infection

After entering the system Doomjuice copies itself to the Windows System Directory as 'regedit.exe'. The copy is added to the registry as

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\NeroCheck HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\NeroCheck

Distributed Denial-of-Service Attack

Doomjuice.B attacks www.microsoft.com via HTTP protocol like Doomjuice.A, but it tries to improve the Distributed Denial-of-Service attack. It sets random HTTP headers to make it more difficult to filter out the attack traffic:

 User-Agent: Mozilla/4.0
 User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
 User-Agent: Mozilla/4.0 (compatible; MSIE 5.0; Windows NT 5.0)
 Accept-Encoding: gzip, deflate
 Accept-Language: en
 Accept-Language: en-us

In addition, this variant starts 32-182 parallel threads to download the main page in an infinite loop, instead of the 16-96 of the previous variant.

The attack will trigger after 12th of February.

For more information on Doomjuice.A see:

http://www.f-secure.com/v-descs/doomjuice.shtml

Detection

Detection in F-Secure Anti-Virus was published on February 11th, 2004 at 10:09 GMT in update:

Version=2004-02-11_01

Description: Mikko Hypponen and Katrin Tocheva February 11th, 2004

Technical Details: Gergely Erdelyi & Ero Carrera; February 11th, 2004;

F-Secure Corporation