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You know those distorted letters and numbers you have to retype to log into websites? They're called captchas, for Completely Automated Public Turing Test to Tell Computers and Humans Apart. One thing they're good for is preventing spambots from signing up for Yahoo email accounts. Or at least that's one thing they used to be good for.

Russian hackers blogging under the name John Wane recently announced they've created an automated system which can recognize the numbers and letters in Yahoo's captchas 35 percent of the time. What does that mean to you? More spam from yahoo.com accounts!

It's not good news for Yahoo, either. During yesterday's earnings call, president Sue Decker noted Yahoo Mail as one of the crucial aspects to the company's drive to build "starting points" to gather higher-quality traffic for paying advertisers. I don't think Russian spammers was the audience she had in mind.