Hacking the Xbox

Chapter 13 - Onward! 205
between the tamper-resistant secure cryptomodule in the local machine
and the authentication server. False system identification would require
either extracting the key from a tamper-resistant secure cryptomodule
(possible, but not trivial and most likely destructive to the module), or
somehow tricking a secure cryptomodule from another registered,
trusted machine into providing the falsified identity.
The SPAM device can be manufactured for relatively little (high performance
FPGAs can cost as little as $50 today in single quantities), and can
be very easy to install. The SPAM can be either integrated directly into a
memory module (in which case it functions as both a trust violation
device and as a memory expansion device), or it can be provided as a
device that is installed in a stacked configuration in between the
motherboard’s memory slot and the existing memory device. In some
memory card configurations, particularly ones that employ heat shields, it
may be possible to hide the SPAM device and pass the module off as a
regular memory expansion device. While elaborate, this may be a
worthwhile attack against a large corporation or bank that stores highvalue
secrets on a trusted PC-based server.
Looking Forward
When considering the prospect of trusted computing, we need to first
consider whether the currently proposed schemes will offer all the
benefits that they promise, and then weigh those against the potential
harm to consumers’ rights and the potential benefits to criminals
(enhanced privacy can be used for both good and ill). If trusted computing
could provide perfect security for online businesses, then that might
be worth the potential risks. However, the scenarios outlined in this
chapter indicate that the trusted PC’s security may be less than perfect.
Consider the Xbox. The Xbox is a trusted PC implementation that can
be hacked with just a $50 solderless module. This places a fairly strong
bound on the value of secrets that can be trusted to an Xbox. Hardware
modchips are so inexpensive that they pay for themselves with the cost of
a copied game title, or two games if you elect to pay someone to install
the chip for you.
Of course, there are always the moral and social implications of stealing
content too, as well as new legislation, such as the DMCA, which aims in
part to make such acts a crime. Unfortunately, the current trusted PC
proposals on the table are also weak in the face of similarly inexpensive
hardware attacks. Thus, it is unlikely that they will provide the level of
security required for high-value or very embarrassing secrets.
The fact of the matter is that hacking technology will be developed
whether or not it is illegal, and whether or not the intention is good or
evil. Thus, it is in the best interests of consumers and companies to
educate the population about hacking, and for everyone to understand
the limitations of their “trusted PC.” The worst-case scenario would be