Kemp’s Blog

A technical blog about technical things

Securing your code

This article on the Xbox-Linux site provides a background of all the exploits found for the Xbox to run non-Microsoft code, but more interestingly it finishes off by giving some very good guidelines for implementing security in any system. Well worth reading in my opinion, especially if you are working on making secure software/hardware.

As a related note, the article reveals that Microsoft’s “don’t talk to anyone outside, don’t compromise” policy played a very large part in the downfall of the Xbox security.

But the Xbox Linux Project did not blindly release this hack. The first savegame proof of concept exploit had been finished in January 2003. After that, a lot of energy was invested in finding out a way to free the Xbox for homebrew development and Linux, but not allowing game copies. Microsoft was contacted, but without any success. They just ignored the problem.

Finally in July, the hack was released, with heavy obfuscation, and lockout code for non-Linux use. It was obvious that this would only slow down the “hacking of the hack”, so eventually, people would be able to use this vulnerability for copied games, but since Microsoft showed no interest in finding a solution, there was no other option than full disclosure. The suggestion of the Xbox Linux Project would have been to work together with Microsoft to silently close the security holes and, in return, work on a method to let homebrew and Linux run on the Xbox.


Microsoft refused to talk about the savegame and font vulnerabilities. If we had been bad hackers, we could have released both of them as-is, immediately making it possible to run copies on Xboxes without the use of a modchip. Instead, we sought contact to Microsoft: We would have preferred to see a backdoor for Linux in the Xbox security system, instead of a solution based on our findings that would allow running copies. But as they refused to talk, we were forced to release the exploits, and they were lucky we heavily obfuscated our solutions so in order to slow down people interested in using it for copies.