Virus.Boot-DOS.Shark.2531 or Shark are some virus that runs on MS-DOS boot.
Shark are dangerous memory resident encrypted stealth parasitic viruses. They trace and hook INT 21h, and write themselves at the end of COM- and EXE-files are executed, they delete some anti-virus programs. The viruses contain the internal text strings (the second string contains the beginnings of the file names, the viruses delete these files on their execution):
AVALANCHE/Germany '94...Metal Junkie greets Neurobasher F-PR TBAV SCAN MSAV CPAV TBME TBFI TBSC VIRS TBDR