Businesses have estimated that recent cyber attacks have caused more than $65 billion in damage, but worm and virus creators are able to use their technical skills to cover their tracks, making arrests extremely rare.

U.S. Attorney General John Ashcroft (search) has said it is "a top federal law enforcement priority to stop crime on the Internet" and his administration has prosecuted more computer crime cases than any other. But when it comes to catching the authors of the countless debilitating computer viruses there have only been a small handful of U.S. arrests.

"The enemy's formidable cyber skills make the cases tough," said John Malcolm, deputy assistant to the U.S. attorney general. "These people are skilled ... at ... executing their crimes in sophisticated ways and then covering their digital footprints immediately."

Computer security experts say anyone sophisticated enough to write a virus could easily figure out how to cover his or her tracks.

"I could do a couple of quick things on my laptop ... that you would not be able to trace me very easily," said Kurt Roemer, security research director for NetContinuum (search), a provider of Web security appliances. "And if I didn't brag about it to my friends or post it in a newsgroup ... then you are not going to find me."

The FBI (search) has tools for virus tracking but they say some victimized companies refuse to cooperate with investigators.

Microsoft is one company trying to make a difference -- in November it announced a $5 million reward for anyone providing tips that can help law enforcement catch virus creators.

"Law enforcement can't do this on their own ... and industry can't do this on its own," said Tim Cranton, a senior attorney for the software giant. "It's a huge problem."

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