[Zac Franken] gave a good talk on authentication systems. (Card readers, biometric systems, etc). After a good introduction to various access control systems, he demoed an excellent exploit tool. Rather than focus on the access mechanism, he exploited the lack of reader installation security. Most card readers are secured by a plastic cover and a pair of screws. Inside, the reader wires are vulnerable. [Zac] put together the equivalent of a keyboard sniffer for the reader wiring. With this little device in place, he was able to collect access codes and use them to exploit the reader authentication system.
The operation goes like this: Install the sniffer. Let it collect some codes. On return, [Zac] is able to use his own card to become a pseudo authenticated card owner, restrict and allow access to other cards. That’s it. No sneaking up behind people to read their cards, just a few minutes with a screwdriver.
He’s not releasing the design, simply because measures to prevent this type of intercept/control mechanism would be extremely costly.