Summary

AntiCMOS is a typical boot sector virus infecting master boot sectors on hard disks and boot sectors on diskettes.

The virus infects a hard disk only if the user tries to boot from an infected diskette. If the hard disk is infected the virus infects practically all diskettes that are used in the computer.

AntiCMOS.A has an activation routine that tries to modify the setup information in the CMOS memory. AntiCMOS.B tries to play a tune. Due a bug in the code, neither of these routines will probably ever get to be executed.

AntiCMOS virus was first found from Hong Kong in January 1994. It's now common all over the world.

The AntiCMOS.B variant contains a text string 'I am Li Xibin'.

[Analysis: Mikko Hypponen, F-Secure]