The virus appears in user's e-mail baskets as a link to a URL urging unsuspecting users to click on the "link" to see pictures from a party.
But anyone clicking on http://www.myparty.yahoo.com/ inadvertently invokes a small C++ application.
Anti-virus firm, Kaspersky stated: "This is definitely a new technique for manipulating a user that is used by "MyParty" and has already caused a series of infections."
According to Kaspersky, on computers running Windows NT/2000/XP, the worm installs a spy program for remote unauthorised control. In this way, a hacker could gain total control over a victim's computer.
Russ Cooper, who runs the Web advisory, NTBugTraq said in an e-mail to subscribers: "This is a pure social engineering attack. It contains an attachment named as a URL with a .com extension."
The .com file extension is traditionally used to denote applications. Cooper said that if a user double-clicks on it, the application would run.
By mid-afternoon on Monday 28 January more than 600 infections had been found in the UK, according to data from anti-virus specialist MessageLabs.