Threat Description



Category: Malware
Platform: W32
Aliases: Sasser.E, W32/Sasser.E, LSASSS


Sasser.E is an Internet worm spreading through the MS04-011 (LSASS) vulnerability.Sasser.E is a variant of Sasser.D.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

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 "lsasss.exe" process, then delete the file 'lsasss.exe' from your Windows directory and reboot.

For step-by-step instructions, see Microsoft's site:

Technical Details

It has been modified by changing the main virus file name to LSASSS.EXE. Note that this has nothing to do with Windows' LSASS.EXE. Also the port numbers used for the shell and FTP server have been changed.

Also, Sasser.E tries to remove the Bagle worm, unlike earlier Sassers but just like many Netsky variants.

Two hours after infection Sasser.E displays the following message:

For more details on Sasser, see description of Sasser.D.


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