Threat Description

Virus:W32/Tenga.A

Details

Aliases:Virus:W32/Tenga.A, Win32.Gael.3666, Virus.Win32.Tenga
Category:Malware
Type:Net-Worm
Platform:W32

Summary



A program that secretly and maliciously integrates itself into program or data files. It spreads by integrating itself into more files each time the host program is run.



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.

Local Network Disinfection

Tenga is a network-aware parasitic file infector virus. For full disinfection instructions for a local network, please Eliminating A Local Network Outbreak.



Technical Details



Virus:W32/Tenga.A is a virus that infects all executable files.

On executing the infected file, the virus attempts to contact a remote server and download and execute a file. In addition, the virus installs a remote command shell on the infected machine.

Infection

Tenga.A infects files by appending itself to each Windows executable file it finds. The virus also has the ability to scan the network and infect files found in open network shares.

It avoids infecting ntoskrnl.exe and marks each infected executable files with the character `V´ in the old DOS stub header. The marking of the infected files prevents re-infection attempts.

To check if an instance of itself is already running, the virus creates a mutex namedgaelicum.

Execution

Upon execution, it connects to and tries to download and execute http://utenti.lycos.it/[***]/dl.exe

It also connects to http://[***].users.freebsd.at and opens a remote command shell on the affected machine on port 54321.

The virus uses CRC matching to search for the required APIs it needs to do its malicious tasks.

Tenga.A also elevates its privileges and disables Windows File Protection.



Detection


F-Secure Anti-Virus detects this malware with the following updates:
Detection Type: PC
Database: 2005-07-14_01




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