You could be completing a purchase, browsing the the latest news or checking out your Facebook page when suddenly a message pops up on your computer, warning you've just been infected with a virus.
Yikes! But never fear, the helpful pop-up offers a "free virus scan" - or a low-cost software that can fix the problem.
Great! But wait a minute, how did they know you've downloaded something nasty?
They don't know, because you haven't. At least, not yet. You might if you fall for their gambit, which is to get you to either buy something you don't need or download a file that will really mess you up for real.
It's called "scareware," for the obvious reason that the people behind the pop-ups are trying to scare you into taking action without thinking it through. According to the Federal Trade Commission (FTC), which has devoted more time wrestling with this issue in recent months, the "free scan" will invariably find all sorts of problems on your computer that it says can be fixed by paying $40 for a special software.
Once you run the software you are told that all your problems have been fixed. Of course, there weren't any to begin with. But in some cases, that software you paid for could be loading all sorts of unwanted files on your computer.
According to Symantec, maker of Norton anti-virus products, the typical scareware pitch will always try to produce panic as a first response. The scammers will take great pains to produce very legitimate looking pop-up "alert" or "update" windows, the kind you might see from a legitimate anti-virus provider. But the tone will be a lot more alarming.
It can go from bad to worse
Besides spending $40 needlessly you've just handed over your credit or debit card information to a criminal enterprise. If the scammers choose to, they can hit your card for bogus charges or clean out your bank account.
In an emerging threat, they may even resort to extortion. The software you download might take over your PC and hold all your files hostage until you make a ransom payment to get control of your computer again.
Microsoft warns that it has seen cases where scareware, once downloaded to a victim's PC, has disabled Windows security updates and even disabled legitimate antivirus software. The company says the rogue software might also attempt to spoof the Microsoft security update process.
Be careful when searching for antivirus software
Rogue security software might also appear in the list of search results when you are searching for trustworthy antispyware software, so it is important to be selective about what software you choose. It should be a brand you are familiar with. If you haven't heard of it, look for online reviews from several different sources.
Who are the scammers behind scareware? Many are offshore, operating in Russia, China or other countries safely outside the jurisdiction of U.S. law enforcement. But every once in a while consumer authorities find domestic scareware operations.
Late last month a federal appeals court handed the FTC a victory when it upheld the $163 million judgment a lower court imposed against Kristy Ross for her role in a scareware operation. In 2008 the FTC charged Ross and six other defendants with running a scareware scheme that defrauded consumers. The other defendants either settled the charges or had default judgments entered against them.
If you have fallen victim to this scam, you may be able to undo the damage to your computer without professional help. Computer experts at Indiana University (IU) say scareware files can piggy-back with browser add-ons, custom social networking media or chat platforms, games, or online advertisements. Fortunately, they tend to be few in number, install themselves in one of a few possible hidden locations, and can be deleted easily once you're able to access and modify the file system.
The IU experts walk you through the process here.