Lyceum

Variant:Lyceum-1788

Other:Resident, COM/EXE-files

Repair:Yes

When an infected file is executed, the virus goes memory resident and hooks three interrupts, 8h (timer), 9h (keyboard) and 21h (DOS). INT 8h increments an inactivity timer and INT 9h resets it. If no keyboard input occurs for about 30 minutes, a dialog box is put up on the screen and is removed at the next keystroke or after a further 30 minutes inactivity. The dialog box contains some unknown foreign text and it is encrypted in the virus code.

If the virus is active in memory, it will infect all files which are either executed or opened or their attributes changed. Infection is attempted on files in the current directory (including hidden files), matching either *.CO? or *.EX?. Virus also checks whether the file begins with AI*.* and if it does, the virus will not infect it.

Non-EXE files are not infected if they're smaller than 1kB or larger than 60kB. The infection signature is 0FCh as the last byte of the file. Virus adds 100 years to the years field in the file date and zeroes the second field. If the free disk space is less than 4 sectors, virus will not attempt infection.

Variant:Lyceum-1832

Other:Resident, COM/EXE-files

Repair:Yes

More advanced version, also able to infect EXE files. Probably written by the same author as other two variants of Lyceum virus.