A driver in Estonia hacks his Renault's TomTom head unit just to change the clock for daylight saving time
A funny and very detailed hardware-hacking story: no time setting without a DRM-locked map card, then a clever trick to get root on a 2011-era Linux unit.
Rasmus Moorats drives a 2014 Renault Latitude. When Estonia switched to winter time, he found the dashboard had no way to set the clock: the TomTom Carminat LIVE unit reads the menu entry for its Settings screen from the navigation SD card, which DRM ties to a specific card, and the previous owner had thrown the card away. A replacement would have cost about 60 euros shipped.
So he pulled the firmware, a custom TomTom OS on Linux 2.6.28, built an emulator in QEMU and looked for a way in. Modified update images were rejected, and the SD card and writable partitions were mounted so nothing on them could run. He finally combined a scripting feature that can write a log file anywhere with the kernel's core_pattern setting, then deliberately crashed a system program, so the kernel ran his script as root. After backing up the unit, he found the time is taken from GPS with the local offset stored as a number of minutes in a settings file, which he could then change.
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Core dump
After exploring Jailbreaking my car's navigation system just so I can change the time | nns.ee, for the crash mechanism his trick hijacked, read about Core dump.
Explains core dumps, the recorded memory and processor state of a program at the moment it crashes, which the kernel can hand to another program.
Wikipedia · Wade · 5 min
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Right to repair
After exploring Jailbreaking my car's navigation system just so I can change the time | nns.ee, for the bigger debate over owning your car's software, try Right to repair.
Covers the legal right for owners to maintain, repair or modify their own products, including automobiles and electronics.
Wikipedia · Wade · 5 min
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