Category:	Malware
Type:	Trojan-Proxy
Platform:	W32
Date of Discovery:	March 29, 2007

This type of trojan allows unauthorized parties to use the infected computer as a proxy server to access the Internet anonymously.

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.

Trojan-Proxy:W32/Grum.A may arrive in the system in a spam e-mail message containing an image that links to the real malware.

Here is the image associated with the message:

This malware is hosted at the following links:

Click here for details about spam on our weblog.

Installation

If the user executes the file they are directed to by the spam message, it creates a copy of itself on the user's computer at the following path and filename:

Grum.A uses the following batch file created on the same directory where the malware was to delete the executed copy of itself:

To enable automatic execution upon system boot, it adds the following auto start registry:

Note: %temp% is the temporary windows folder:

Activity

Once installed, Grum.A serves as a proxy server that communicates to the following address:

Commands from the server may include downloading of files and spamming mails.

Stealth

Grum.A is a kernel malware that hooks several ntdll APIs to hide its file and process.