Original infection from email, natch.
One of the little critter's tricks is to search out shared printers and print out it's compiled code. About 500 pages of printout with one or two lines of garbage on an otherwise blank page.
"A civilian gang of thieving lobbyists for the military industrial complex is running the White House. If to be against them is considered unpatriotic -- Hell, then call me a traitor."
-- Hunter S. Thompson