Virus.Boot-DOS.Shark.2531 or Shark is a virus that runs on MS-DOS boot.
Shark is a dangerous, memory resident, and encrypted virus. It traces and hooks INT 21h, and writes itself at the end of COM- and EXE-files are executed. The virus can delete some anti-virus programs. The virus contains these internal text strings (the second string contains the beginnings of the file names, the viruses deletes said files on the virus's execution):
AVALANCHE/Germany '94...Metal Junkie greets Neurobasher F-PR TBAV SCAN MSAV CPAV TBME TBFI TBSC VIRS TBDR