Threat Description



Aliases: Shell, Tentacle_II
Category: Malware
Platform: W32


This virus was found in the wild in June 1996 in USA, UK, Australia, Norway and New Zealand. It has possibly been distributed over the internet several times.


Automatic Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.

Technical Details

A known infection happened on the 3rd of August, 1996, when an infected screen saver called PCTRSHOW.ZIP was posted to the following newsgroups:

Do note that there are also clean copies of PCTRSHOW in circulation.

The virus infect only Windows 3.x executables (NE), and it does it without changing the executable entry point. This is an unusual infection method and was first introduced in this virus.

When executed, Shell.10634 searches the directory tree for suitable files to infect. Only EXE and SCR (screen saver) files can get infected.

Also 32bit Win95 and WinNT executables can be infected by the virus, but these files are unable to spread the infection further. Shell not stay resident in memory.

This virus activates by dropping a GIF file, which contains a picture of a Tentacle and text:

  I'm the Tentacle Virus!

The author of this virus also wrote the Tentacle and Tentatrickle viruses, which are technically quite different from this virus. See: Tentacle

Description Created: Mikko Hypponen, F-Secure


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