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Sasser.F

Classification

Category: Malware

Type: -

Aliases: Sasser.F, W32/Sasser.F, Worm.Win32.Sasser.a

Summary


Sasser.F is a minor modification of the Sasser.A worm. It shares all of its code and functionality, although it uses a different filename when copying itself into the system and a different mutex name.

Removal


Automatic action

Once detected, the F-Secure security product will automatically handle a harmful program or file by either deleting or renaming it.

Eliminating a Local Network Outbreak

If the infection is in a local network, please follow the instructions on this webpage:

Manual Disinfection

To manually disinfect an infected system, first apply the Microsoft patch MS04-011, then use Task Manager to kill the 'napatch.exe' process, then delete the file 'napatch.exe' from your Windows directory and reboot.

For step-by-step instructions, see Microsoft's site: https://www.microsoft.com/security/incident/sasser.asp#steps

Knowledge Base

Find the latest advice in our Community Knowledge Base.

About the product

See the manual for your F-Secure product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details


Sasser.F is an unpacked, edited and repacked version of Sasser.A.For full details, please refer to the Sasser.A description.

System Infection

When the worm enters the system it creates a copy of itself in the Windows Directory as 'napatch.exe'. This copy is added to the Registry as

[SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
 "napatch.exe" = "%WinDir%\napatch.exe"

To ensure that only one copy of the worm is running it creates a mutex named 'billgate'.