ICE and the Computer Crimes Center did not respond to calls Monday. PayPal and eBay were unable to comment immediately.

Criminals are finding plenty of ways to steal money in the U.S. The hard part, though, is getting the cash out of the country. That's where money mule networks come in. In October, authorities arrested more than 100 people in the U.S. and U.K. in connection with -- this one thought to be operated out of Ukraine. Scammers were hacking into bank accounts, transferring money around, and then using mules to move the money offshore using services such as Western Union.

The IDG News Service