Computer's Heat May Unmask Anonymized PCs

Wired is carrying a story about a method developed by security researchers to identify computers hiding behind anonymity services. From the article: 'His victim is the Onion Router, or "Tor" — a sophisticated privacy system that lets users surf the web anonymously. Tor encrypts a user's traffic, and bounces it through multiple servers, so the final destination doesn't know where it came from. Murdoch set up a Tor network at Cambridge to test his technique, which works like this: If an attacker wants to learn the IP address of a hidden server on the Tor network, he'll suddenly request something difficult or intensive from that server. The added load will cause it to warm up.

"When a crystal is manufactured, it has a clock skew, and it's different for each crystal (throughout its) lifetime," explains Steven J. Murdoch, a Cambridge University researcher who discussed his work at the Chaos Communications Congress on Thursday.

- [Via]