DuckCorp Dico

Found one definition

1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   phage
      A program that modifies other programs or databases in
      unauthorised ways; especially one that propagates a virus or
      Trojan horse.  See also worm, mockingbird.  The
      analogy, of course, is with phage viruses in biology.
      [Jargon File]