A new breed of fake anti-virus program has been spotted in circulation and actually installs malware on your PC rather than simply informing you of infections.
Traditionally, fake anti-virus programs misreport genuine files to be malware in the hope of persuading you to fork out to clean your PC of the 'infection'.
However, researchers at Sophos have spotted a fake anti-virus program - also known as rogueware - which actually installs malware files on your PC in an attempt to convince you that it is genuine.
Sophos' Chee Hui said: "Instead of blatantly and randomly misreporting files as malware, what this Trojan has done is to deliberately spawn/create new junk files on the infected computer, with random names and random file extensions and proceeded to detect them."
Rogueware programs are nothing new, with several new variants being spotted in recent weeks.
However, these cheeky new tactics are likely to rile surfers and security firms further.
"To top it all off, like all other FakeAVs, this Trojan also periodically pesters you with annoying pop-up messages asking you to buy their product. And I thought such applications can’t get more annoying, was I wrong indeed!" Hui said.