Threat Description

SemiSoft

Details

Aliases: SemiSoft, Net.666
Category: Malware
Type:
Platform: W32

Summary


This virus infects Windows EXE files. It spreads natively under Windows 95 and NT (making it the fourth known Windows NT -specific virus).



Removal


Automatic action

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

More

Detailed instructions for F-Secure security products are available in the documentation found in 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.



Technical Details


After infecting a machine and waiting for some time, the virus sends a "ping" to four IP addresses located in New Zealand to announce which machines it has infected. After this, the infected machines open up port 531 for incoming connections, and the machines can be controlled by sending commands to this port.

There are several variants. The first 60416 byte variant contains these texts:

mylen=, c:\testexe.exe, NOTEPADX.EXE, NOTEPAD.EXE, SETUP.EXE,         EXPLORE.EXE, EXPLORER.EXE, WINIPX.EXE, WINIPXA.EXE,         WINSRVC.EXE, E5.2, DEBUG, IMPL=         ETHP v5.2         \IDENT.TXT  

When the virus is active, it is visible in the process list as a number, typicly "6.666". When exiting Windows, NT sometimes complains it can't close a task by this name.

SemiSoft was known to be in the wild in the end of 1997 and beginning of 1998.

[MHH//DF]






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