The adware dropping bug was first discovered on July 14 and identified by Trend Micro as a new version of the Opanki.Y worm. It arrives in a message with text reading, "this picture never gets old" with a link to download a file called iTUNES.EXE, fooling users into thinking they will receive a legitimate iTunes music file of the same name.
Once downloaded, the worm installs four adware programs, opening a back door to the infected PC. It can then use the affected system as a launch pad to spread the worm as well as circulate it to the user's online contacts.
The worm is programmed to run on Windows 95, 98, ME, NT, 2000, XP and Server 2003.
Although Trend Micro rated the threat as low, those using instant messenging services are advised to use up-to-date antivirus software and to be cautious when clicking on links in messages, even those seemingly sent by friends.