A security hole in a common technology used to manage prepaid store cards could let malicious hackers and other criminal groups bilk FedEx Kinko's stores, according to a recently published report. ExpressPay is a system developed by EnTrac Technologies, of Toronto. The system uses smart cards from Infineon, but does not secure data on the cards. A security hole could allow hackers to <A HREF="http://www.eweek.com/article2/0,1895,1932824,00.asp">clone legitimate cards</A> or change the value of a card to any amount, according to Strom Carlson, a hardware security researcher at Secure Science in San Diego. The report is just the latest warning about vulnerabilities in cash card technology, which is becoming a popular tool for money laundering.