Security researcher Samy Kamkar has developed an attack for fixed-code garage door openers. To showcase the attack, called Open Sesame, Kamkar reprogrammed a children's toy designed for short-distance texting.
Although the fixed codes of garage door openers can be cracked through brute force, it was believed to take longer. The remote controller always transmits the same 8- to 12-bit binary code, and the process to iterate all the possible combinations would take 29 minutes, according to Kamkar's calculations.
However, retransmitting the same code five times is unnecessary along with the wait time between each bit, and when Kamkar removed those steps he found the time needed to brute-force the code was only about three minutes. Kamkar then found when the opener interprets a continuous string of bits, it does not test the first 12 bits as a possible code and then the next 12 bits, and so on. Kamkar developed a sequence that includes each combination of bits only once. He says this algorithm produces every possible overlapping sequence of 8 to 12 bits in eight seconds, but the correct code typically will be found in less time.
From IDG News Service
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