A new variant of the MyDoom worm, described variously as MyDoom.Q or MyDoom.O, was discovered on Tuesday that uses Yahoo's People Search to find new email addresses.
Last week, a MyDoom variant pumped so many queries into Google that the search engine was unavailable or very slow for large periods of time. The same variant of MyDoom also succeeded in knocking a number of smaller search engines -- including Lycos and Altavista -- off the Web completely.
Graham Cluley, senior technology consultant at antivirus firm Sophos, said he is not surprised that another MyDoom variant has been released and expects future variants to continue harvesting email addresses from search engines.
"You don't have to be psychic to predict the release of more worms trying to scoop up email addresses from search engines. Unfortunately, we expect to see other worm authors trying similar tricks in the future," said Cluley.
Earlier this year, both Microsoft and SCO each offered a $250,000 reward to anyone providing information that helped catch the worm's author.
"Someone in the computer underground must know the person or people behind MyDoom. Those with knowledge which may help the investigation should come forward now and pass their information onto the authorities," said Cluley.
Finnish antivirus firm F-Secure has gone one step further and posted a "job advert" on their Web log offering readers a chance to "make money fast" by finding the author of MyDoom and cashing in on the rewards.
An entry posted on Tuesday evening, just after the latest variant was discovered, tries to persuade spammers and other members of the hacking underground to contact the FBI.
"If you have information on the origin of MyDoom, you're most likely connected to spamming in one way to the other (as MyDoom is used to create spam proxies). So you should be able to appreciate money. $250,000 is a lot of money. Think about it," said the Web log entry.
At the time of writing, Yahoo People was functioning normally.