You can see the results of this activity. A Google search for the term "Microsoft Office 2002 download" yields a Microsoft.com redirection link as its first result. That link had been redirecting visitors to a malicious Web site, which launched Web-based attack code against victims and tried to trick them into downloading fake antivirus software, Warner said. By Tuesday evening, Microsoft had fixed the problem, so the Microsoft.com link that pops up in the google search results was no longer taking surfers to the malicious Web site.

The IRS has now addressed the issue too, but about 20 other sites remain a problem Warner said.

The fake antivirus software, also called "scareware," installs a keylogger on the victim's computer, presumably to steal login names and passwords, and also launches fake warning popups on every Web page that the victim visits telling him he needs to buy antivirus software, called System Security. The price for the fake product? A believable-sounding $51.45.

The FTC estimates that 1 million consumers were taken in by other fake antivirus products which go by names such as WinFixer, WinAntivirus, DriveCleaner, ErrorSafe and XP Antivirus. On Dec. 10 a federal court ordered two companies, Innovative Marketing and ByteHosting Internet Services, to stop promoting these products.

Warner doesn't know who is behind System Security, but he believes that the scammers behind this latest operation may be connected to the earlier scams. "It's similar enough that it's got to be somebody who has a relationship with the last group," he said.