[jdeeny]

An EEPROM (Electrically Erasable Programmable Read Only Memory) is erased electrically rather than with UV light like an EPROM. Even if there isn't a possible attack with light, there might be a way to alter the contents of the EEPROM if you can manage some amount of control over the signals entering the IC.

[teuobk]

It turns out that part of the attack does exactly that. It was glossed over in the Wired article, but the slides describe how the lockout-penalty feature in the lock was defeated by manipulating the EEPROM. Basically, if you kill power to the lock at just the right time (i.e., midway through the EEPROM erase cycle as part of the larger/longer EEPROM write cycle), those bytes in EEPROM will be left with a value of 0 instead of whatever had been there.