Click here - but definitely not there

Several readers have mentioned an unusually virulent Internet virus they've been fighting. When one said he might have to trash his laptop, or at least wipe the hard drive clean, it seemed worth taking notice (even though I'm a smug Mac user, at least outside the office).

The name of the virus - "Internet Security 2010" - is a clue to what it is, and how it likely infected their computers. It mimics the name of the popular Norton anti-virus product that this year is called "Internet Security 2010."

I caught up today with Marian Merritt, who holds the title of Norton Internet Safety Advocate. Her job  for Symantec, which makes the Norton software, is to help computer users cope with the ever-changing nature of Internet threats.

Merritt says the virus - she clearly doesn't like to use its Nortonesque name - is just one of many recent examples of an old phenomenon: viruses or Internet trojan horses that masquerade as legitimate anti-virus software.

The genius of this kind of malicious software (malware) is that "it works beautifully on relatively sophisticated consumers," Merritt says. She says Norton saw a spike in the problem last year, and the plague continues.

It's definitely malicious. A cybercriminal writes code for a pop-up window that appears to announce it’s scanning your computer. You click a link, thinking you're doing the smart thing. Instead, you allow malicious code onto your computer.

Typically, the malware then tells you you're definitely infected, and offers to clean your computer for a price - say, $60. If you bite, you've now just given your credit-card info to potential identity thieves. Meanwhile, the program disables your actual anti-virus programs, opening the way to all sorts of mischief.

I'll tell you more about how to protect yourself in future blog posts. Meanwhile, if you want to read Symantec's most recent "Report on Rogue Security Software," click here. For the executive summary (PDF), click here.

The best solution (other than using a largely immune Mac) is to keep your security software - and all your other software - up to date. You have to keep up with the bad guys, and they're moving fast.