Threat Description

Trojan-Proxy: W32/Grum.A

Details

Category: Malware
Type: Trojan-Proxy
Platform: W32
Date Discovered: March 29, 2007
Aliases: Trojan-Proxy:W32/Grum.A

Summary


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



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.



Technical Details


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:

  • http://tvz-archive.com/I[REMOVED}.exe
  • http://abnoba.net/I[REMOVED]0.exe

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:

  • %temp%\winlogon.exe

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

  • sys.bat

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

  • HKCU\\Software\Microsoft\Windows\CurrentVersion\Run Firewall auto setup = %temp%\winlogon.exe

Note: %temp% is the temporary windows folder:

Activity

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

  • 72.232.49.214

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.






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