wraggster
November 10th, 2013, 20:04
http://hackadaycom.files.wordpress.com/2013/11/phonecracking.jpg?w=280&h=450
[Brett's] girlfriend is very concerned about cell phone security — So much so that she used a PIN so secure, even she couldn’t remember it. (http://www.bbrotherton.com/main/androidpinbruteforce)
Beyond forgetting the PIN, the phone also had encryption enabled, the bootloader locked, and zero permissions for the Android Device Manager to change the PIN. Lucky for her, [Brett] had purchased an STM32F4Discovery Development Board a few months ago, and was itching for a suitable project for it.
Now unfortunately, Android allows you to pick a PIN of anywhere between 4 and 8 digits, which as you can guess, results in a massive number of possible permutations. She was pretty sure it was only 6 digits, and that she didn’t use a 1, 2, or 3… and she thought it started with a 4 or a 7… and she didn’t think any of the digits were repeated… This helped narrow it down a bit, from 1 million possibilities to about 5,000 — assuming all of the boundary conditions she remembers are in fact correct.
[Brett] started by writing a C library to generate permutations of the PIN, testing the board on his own phone to make sure it works with a known PIN, and boom, they were in business.
28,250 PIN attempts later, they decided they were not. Did we mention you can only enter 5 PINs in every 30 seconds?
http://hackaday.com/2013/11/10/brute-forcing-an-android-phone/
[Brett's] girlfriend is very concerned about cell phone security — So much so that she used a PIN so secure, even she couldn’t remember it. (http://www.bbrotherton.com/main/androidpinbruteforce)
Beyond forgetting the PIN, the phone also had encryption enabled, the bootloader locked, and zero permissions for the Android Device Manager to change the PIN. Lucky for her, [Brett] had purchased an STM32F4Discovery Development Board a few months ago, and was itching for a suitable project for it.
Now unfortunately, Android allows you to pick a PIN of anywhere between 4 and 8 digits, which as you can guess, results in a massive number of possible permutations. She was pretty sure it was only 6 digits, and that she didn’t use a 1, 2, or 3… and she thought it started with a 4 or a 7… and she didn’t think any of the digits were repeated… This helped narrow it down a bit, from 1 million possibilities to about 5,000 — assuming all of the boundary conditions she remembers are in fact correct.
[Brett] started by writing a C library to generate permutations of the PIN, testing the board on his own phone to make sure it works with a known PIN, and boom, they were in business.
28,250 PIN attempts later, they decided they were not. Did we mention you can only enter 5 PINs in every 30 seconds?
http://hackaday.com/2013/11/10/brute-forcing-an-android-phone/