Heard the one about the Skype worm? Actually, users of the popular VoIP service Skype have been contending with misleading and dangerous URLs for some time. Like worms spread by MSN Messenger and Yahoo Messenger, various Skype worms have been known to include a message such as "Give me your opinion" followed by a URL. Clicking the link then installs several malicious files including versions of the Warezov/Stration Trojan horse. Stration has been known to open remote access on infected machines.
Now, Chris Boyd, Director of Malware Research at Facetime Security Labs, has found a recent Skype worm variant that is able to infect not just Skype, but ICQ and MSN Messenger, with the potential to infect AIM, Trillian, and Yahoo Messenger as well. While looking at a collection of Skype worm code posted on the Internet, Boyd found a file that looks for other instant messenger services. While attacks via Yahoo and MSN are not new, we haven't seen a lot of IM worms that are able to jump the fence and attack other services. Thus, if you have Skype, and click the link, you may infect contacts you have on other IM services as well.
Our recommendation? Don't be so quick to click.