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Behind the Xbox Boot Code

Posted by Zonk on from the bowels-of-the-machine dept.

NiteStar writes "The Xbox-Linux team has up a new article about The Hidden Boot Code of the Xbox. The Xbox console contains a 'chain of trust' to allow only legit Microsoft signed code to run on the Xbox. The hidden 'MCP' boot ROM (just 512bytes) is the link between hardware and software in this chain of trust." From the wiki article: "The Xbox, having an external (reprogrammable) 1 MB Flash ROM chip (models since 2003 have only 256 KB), would normally start running code there as well, since this megabyte is also mapped into the uppermost area of the address space. But this would make it too easy for someone who wants to either replace the ROM image with a self-written one or patch it to break the chain of trust ("modchips"). The ROM image could be fully accessed, it would be easy to reverse-engineer the code; encryption and obfuscation would only slow down the hacking process a bit."

2 of 52 comments (clear)

  1. Summary by acaspis · · Score: 5, Informative

    • Due to technical constraints, the Xbox designers had to implement a secure virtual machine in 175 bytes of x86 code, and failed (there are at least two execution paths leading out of the sandbox). But congratulations for trying.

    • They also used a non-cryptographically-secure hash function for authentication (or maybe they didn't have enough space left).

    Nice attempt at a TCPA-like architecture, though. And cheers to the xbox-linux guys for their amazing achievements and enlightening write-up.

  2. OT: Shuttle Failures by cant_get_a_good_nick · · Score: 4, Informative

    Richard Feynman was one of the people who investigated the first shuttle disaster, and as a pain in the ass cantankerous old coot, really didn't care about standard Washington procedures and really got to the core of the matter. He cronicles a lot of it in What Do You Care What Other People Think?, ISBN: 0393320928 (get it from wherever, no Amazon kickbacks here). A very interesting read, I ended up reading it right after the second shuttle disaster, and thought that a lot of the human problems that caused the first blow up could be fingered in the second.

    If you haven't read Feynman before, you'll probably like him. Funny guy, pretty damn smart, and managed with luck, brains, skill and stubbornness to get in the middle of some of the biggest science in the last century.