Skype is best known for allowing subscribers to make free telephone calls over the Internet. The company has more than 7 million subscribers and was acquired just over a year ago by online auction firm eBay for $2.6 billion.
Early reports indicate that the worm sends messages via Skype Chat, an instant-messenging tool. The messages ask recipients to download and run a file called sp.exe.
Once the file is executed, it installs spyware that can steal passwords and other personal information. It also connects to a remote server to download additional code.
According to Websense, the worm seems to have come from the Asia-Pacific region, possibly Korea.
The number of people affected is still unclear.
Munir Kotadia of ZDNet Australia reported from Sydney.
