Summary

AntiExe is a simple boot sector virus, infecting floppy boot records and hard disk master boot records. The virus is very small and it is not encrypted.

AntiEXE uses stealth techniques, so infected boot sectors look clean if inspected while the virus is resident. F-Secure anti-virus products will detect if AntiExe is resident, and will advise you to boot from a clean diskette.

The virus will only infect hard drives when an attempt to boot from an infected diskette is made. Once the virus has infected the hard drive, all non-write-protected floppies used in the machine will be infected.

AntiExe virus redirects the BIOS disk interrupt 13h to unused interrupt D3h - this way the virus can bypass some behaviour blocker programs.

AntiEXE targets an unknown EXE file, sized 200768 bytes (memory size 200256 bytes). Whenever this specific EXE file is accessed, the virus prevents it from running.

AntiExe is very common all over the world.

[Analysis: Mikko Hypponen, F-Secure; thanks to S. Widlake for pointing out an error in the description and Alan Candy for providing additional details]