This is a small and tricky boot sector virus.It spreads like a typical boot virus: if only infects a hard drive if you boot with an infected floppy in drive A:. After that it will infect all floppies that are accessed in the machine.The code of the virus contains several little tricks, and it seems to be written by an experienced programmer.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
On floppy disks, the virus formats an extra track and stores the original boot sector there. On hard drive, the original MBR is stored on sector 8.The end of the virus contains this unencrypted text which is never displayed:
SPIRIT (c) MW
Spirit does nothing besides replicating.Spirit was reported to be in the wild in the Netherlands in March 1996 and in the USA and Finland in April 1996.
Technical Details: Peter Szor, F-Secure, 1996