It's a memory resident very dangerous virus. It hooks INT 21h and infects by a standard manner executed EXE-files. It contains the text "WitCode". Depending on the current time and date it can write 2 bytes into the first 2 bytes of the Boot-sector. This 'corrected' boot sector hangs up while booting. This virus also decrypts and types one of the messages:
Gee, I wanna sleep now!
Merry Christmas!
You really shouldn't work on Sundaysall
You got a fine machine!
