Pair of PC viruses help each other survive

[Clive]

Two computer viruses that collaborate are proving hard to clean from infected PCs, Microsoft research suggests.  The pair of viruses foil removal by regularly downloading updated versions of their malware partner.

http://www.bbc.co.uk/news/technology-23125422

[Steve]

Dare I say that's very clever but obviously no fun if your infected!

[nowster]

Not a new concept. Was done in mainframe days.