Virus Profile: W32/Gibe@MM

Virus Characteristics

-- Update March 12, 2002 --
To date, more than 50% of the W32/Gibe samples received are damaged. The file header is corrupt. Therefore, the files do not run or infect. The 4190 DATs include detection of these corrupted files as W32/Gibe.dam.

This mass-mailing worm masquerades as a Microsoft Security Update patch (named Q216309.EXE) in order to dupe users into executing it.

The worm is intended to be able to mail itself using both Microsoft Outlook and the default SMTP server for the victim machine. However, in testing the worm was buggy, and did not successfully use Outlook to spread.

Once executed, the worm retrieves the default Internet Account details from the Registry, and creates the following keys, writing this data there:

• HKEY_LOCAL_MACHINE\Software\AVTech
• HKEY_LOCAL_MACHINE\Software\AVTech\Settings "Default Address"
     (default SMTP email address)
• HKEY_LOCAL_MACHINE\Software\AVTech\Settings "Default Server"
     (default SMTP server)
• HKEY_LOCAL_MACHINE\Software\AVTech\Settings "Installed"
     = ...by Begbie

The WINNETW.EXE component of the worm queries two Internet-based email address directories. It parses email addresses from the returned data, writing them to 02_N803.DAT (repeatedly).

The following two Registry keys are set in order to run the worm components:

• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run_
     "3dfx Acc" = %windir\GFXACC.EXE
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run_
     "LoadDBackup" = %windir\BCTOOL.EXE

Upon restarting the machine, BCTOOL.EXE runs, mailing the worm to all the email addresses listed in 02_N803.DAT, using the default SMTP server.

The final component of this worm, GFXACC.EXE, is a backdoor Trojan, opening port 12378 on the infected machine. This component is detected as BackDoor-ABJ by the indicated DATs.