Threat Description

Trojan-Proxy:W32/Grum.A

Details

Aliases:Trojan-Proxy:W32/Grum.A
Category:Malware
Type:Trojan-Proxy
Platform:W32

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

You may wish to refer to the Support Community for further assistance. You also may also refer to General Removal Instructions for a general guide on alternative disinfection actions.



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.






SUBMIT A SAMPLE

Suspect a file or URL was wrongly detected? Submit a sample to our Labs for analysis

Submit Now

Scan & clean your PC

F-Secure Online Scanner will scan and clean your PC in just a few minutes for free

Learn More