The FBI have issued a warning on the threat of “scareware” and fake antivirus scams, claiming that the problem costs American computer users a staggering $150m a year.

So-called scareware scams, which attempt mislead users into believing that their PC is infected with some form of computer virus or spyware before encouraging them to download or purchase software that claims to fix the problem, have seen a resurgence in 2009, escalating the issue into one of the biggest concerns for the IT security industry. This has prompted the FBI to issue a warning ahead of the Christmas period, typically the biggest time of year for PC and software sales.

“The scareware is intimidating to most users and extremely aggressive in its attempt to lure the user into purchasing the rogue software that will allegedly remove the viruses from their computer,” the note stated.

“Downloading the software could result in viruses, Trojans and/or keyloggers being installed on the user’s computer. The repercussions of downloading the malicious software could prove further financial loss to the victim due to computer repair, as well as cost to the user and/or financial institutions due to identity theft.”

The FBI estimated that losses through scareware have already reached $150m and is advising users to keep up to date with operating system patches and antivirus software. It is also advising users to familiarise themselves with the names of legitimate security software so they are able to spot the fake brands. Microsoft’s Checkmark Gold certification is considered to be one of the trusted signs of both quality and legitimacy.

“If a user receives these anti-virus pop-ups, it is recommended to close the browser or shut the system down,” said the note.

“It is suggested that the user run a full, anti-virus scan whenever the computer is turned back on.”

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