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Trojan-Proxy:W32/Grum.A


Discovered:
Aliases:


March 29, 2007
Trojan-Proxy:W32/Grum.A

Malware
Trojan-Proxy
W32

Summary

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



Disinfection & Removal

Automatic Disinfection

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

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



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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