Microsoft is trying to put some pressure on the criminals responsible for the worst Internet worm outbreak in years, offering a US$250,000 reward for information leading to the arrest and conviction of Conficker's creators.The software vendor said it was also working with security researchers, domain name registrars and the Internet Corporation for Assigned Names and Numbers (ICANN) to try to take down the servers that have been launching the Conficker attacks. ICANN is the nonprofit corporation that oversees Internet addresses."The best way to defeat potential botnets like Conficker\/Downadup is by the security and domain name system communities working together," said Greg Rattray, ICANN chief Internet security adviser, in a statement released Thursday. "ICANN represents a community that's all about coordinating those kinds of efforts to keep the Internet globally secure and stable."Conficker, also known as the Downadup worm, takes advantage of a critical bug in Microsoft's Windows operating system, which was patched last October. Since late December the worm has emerged as one of the worst computer threats in years, infecting more than 10 million computer systems worldwide, including PCs within the British and French militaries.If Conficker's author lives in a part of the world that's known to be soft on cybercrime -- Russia, the Ukraine or Romania, for example -- it may be hard to get a conviction, said the editor of the Hostexploit.com cybercrime research site, who goes by the pseudonym Jart Armin.On the other hand, the $250,000 reward may be an incentive to hackers who may know who's responsible. Typically, hackers get paid about $10,000 by organized crime groups for writing an attack that reliably works on a significant number of computers, Armin said.This isn't the first time Microsoft has offered such a bounty. In 2005, it paid $250,000 to two people for identifying Sven Jaschan, the teenager who wrote the Sasser worm.