Threat Description



Category: Malware
Type: Virus
Platform: W32
Aliases: S-Bug, SatanBug


S-Bug is a highly polymorphic virus that has been reported to be in the wild in USA and in several other locations.

Virus stays resident in memory occupying 9 KB's of DOS memory. It hooks the following INT 21h functions: 3Dh, 4Bh, and 6Ch. Infected files grow in size between 4k and 5k bytes.

Infected EXE and overlay files may fail to execute correctly. Virus includes string "Satan Bug virus - Little Loc".

The virus will only become resident if the environment variable COMSPEC= is set to point to a file called COMMAND.COM.

S-Bug virus also removes validation codes added to files by McAfee SCAN and CPAV's Immunize function.


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 more information.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details


A related variant. Uses similar encryption, but the actual virus is simpler and non-resident.

See: Natas

Description Details: Mikko Hypponen, F-Secure


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