Microsoft today warned that scammers have taken to the phone lines to dupe Windows users into putting malware on their machines or paying for worthless help.
The ploy isn't new -- security experts have seen it in circulation for at least a year -- but Microsoft was the first to quantify the problem.
According to Microsoft, which sponsored surveys in the U.S., the U.K., Ireland and Canada, 15% of the people polled said they had received unsolicited calls from fraudsters posing as computer support technicians who claimed they were offering PC security checks.
The scammers try to trick users into believing that their computer is infected -- often by having them look at a Windows log that typically shows scores of harmless or low-level errors -- then convince them to download software or let the "technician" remotely access the PC.
The con artists charge for their "help" and often get people to pay for worthless software. In actuality, the software is malware that steals online account information and passwords.
"They're taking advantage of ignorance," said Sean Richmond, a senior technology consultant for Sophos, in a podcast today.
In many cases, the scammer asks the user to open Windows' events log, which records significant events on the PC, including program errors. Richmond noted that the log typically contains scores of such errors, which may look alarming to many users.
Of the people who received such calls, 22% fell for the scam, Microsoft said.
Most who were duped suffered some kind of post-call financial loss, which Microsoft claimed averaged $875 per victim. Among the losses, people cited compromised passwords, balky computers, identity fraud and cash pilfered from their bank accounts.
"Criminals have proved once again that their ability to innovate new scams is matched by their ruthless pursuit of our money," said Richard Saunders, the director of one of Microsoft's public relations teams, in a Thursday statement.
Although the scam currently targets Windows users -- and for now is limited to English-speaking countries -- there's nothing to stop criminals from expanding their scheme. "Presumably, when these guys smarten up a little bit ... they could pull exactly the same trick [on Mac users]," said Paul Ducklin, Sophos' head of technology for its Asian and Pacific division.
Richmond agreed. "The demographics for Mac users is that they have more money to waste, so I wouldn't doubt that they would become a target," he said.
These phone scams aren't new. Last year, for example, Symantec noted similar schemes making the rounds.
"It's a natural extension of the fake antivirus stuff," said Marc Fossi, a director in Symantec's security response team, in an interview today.
Those scams, often dubbed "scareware" or "rogueware," use higher-volume methods -- poisoned search results and spam email -- to trick users into visiting malicious sites that proclaim a PC or Mac is heavily infected. Users are encouraged to download security software to fix the nonexistent problems, but to get rid of the resulting bogus alerts, victims must fork over fees that can reach $80.
Mac users were hit by several scareware campaigns last month, the first time they had been targeted by such scams.
Fossi put the telemarketing tactic in context.
"Fake AV is a much bigger problem than this," Fossi said. "This sounds like a pretty low rate of return on investment [for the criminals] because of the time commitment to do this. But maybe they're getting a higher success rate because [the victim] is actually talking to a real person. Some probably think, 'Why would they take the time to call if there wasn't a problem?'"
Traditional security software won't help users deflect phone calls from fake support technicians, Fossi acknowledged. "It's social engineering, so the only thing you can do is try to educate people," he said.
Microsoft urged Windows users to "be suspicious of unsolicited calls related to a security problem, even if they claim to represent a respected company," and gave other common sense advice, such as to never divulge credit card or bank account information to out-of-the-blue callers.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is email@example.com.