The virus, which F-Secure calls Virkel.F, comes as a file called BETA8WEBINSTALL.EXE that can be downloaded from a Web site. Running the program installs not a new MSN Messenger beta, but rather a virus that sends download links to a computer user's MSN Messenger buddies. The virus falsely labels the link as "MSN Messenger 8 Working BETA."
"It also connects your machine to a botnet server," F-Secure warned, meaning that a person's computer can be controlled remotely to attack other machines or send spam.
Malicious software that uses instant messenger programs is growing more common. A November study by Akonix Systems identified 62 examples.
And Microsoft's instant-messenger infrastructure is the most popular conduit for attack, IMlogic said in an October study.
