Detectives believe credit cards recently used at businesses in these ski towns were infected with malware originating from international locations. Cards infected with the malware cause the server to forward the credit card information on to criminals who can use it to make fraudulent purchases.

"A lot of these network intrusions are coming from the Ukraine, Russia, North Korea and China," Rick Magnuson, a detective with the Aspen Police Department, told Denver’s 9 News. "[Tourists] come here then go home, check their statement a week or two later and see now their credit card has been breached."

Magnuson said the cyber-thieves normally start with small transactions and then quickly move on to more expensive ticket items. “They will run up thousands of dollars in a short time, even one day," Magnuson said.

Law enforcement officials in the impacted mountain communities are notifying the public to be alert to any suspicious activity when making credit card purchases and to check their transaction statements regularly.