A variant of MyDoom worm attacked various seach engines including Google, one of the largest search sites, and caused problems for the company, said security experts. The new variant of MyDoom has also reportedly attacked search engines Yahoo! and Altavista and caused the search websites to significantly slow down.

Security Researchers reported that the new variant targets search sites in hopes of discovering email addresses. After it gets the email addresses, it propagates itself by sending emails to the recipients with infected files.

"Those search requests have been overloading the search engines," said Lloyd Taylor, Vice President of Technology at Keynote Systems, Inc. Keynote Systems, Inc. measures website performance using unique methods.

Yahoo reported that the impact of the worm was minimal and the firm is no longer suffering from its effects.

Security firms started warning their users about the MyDoom.m or MyDoom.o worm. Symantec, a security firm, reportedly received 250 emails inquiring about the worm.

"This is certainly equivalent to what we saw back then," said Oliver Friedrichs, Senior Manager, Symantec Security Response Group.

Security firms are stating that information about the worm is starting to emerge already.