Possessor

Possessor is unusual anti-IC program. Possession attacks the target program in the normal anti-IC manner; if it wins, the program is "turned against" its operating system or Netrunner. The control is rather crude; for instance, Killers will attack the nearest program(s) not belonging to the "possessing" Netrunner. If a Controller is possessed, the thing will simply be operated at random. Demons cannot be "possessed" if they contain an Anti-IC program as one of their subroutines.

Source

 * Chromebook Volume 3, pg.77