What if you want to change the time in your car’s infotainment system, but it’s so locked down that you can’t even open the time settings menu without a very specific, DRM’d SD card? Well, you try to jailbreak it, of course, but the amount of effort required can kind of spiral out of control. And then, all the way at the end, it’s just an offset.
The first thing I did was use this to create a full backup of the internal eMMC using
dd. With a more complete dump of the system, I pretty quickly figured out that the date & time settings that I’m interested in are in/mnt/flash/settings.dat, which is a custom binary format. After some more reverse engineering, it turned out the unit doesn’t really have a concept of timezones at all. It gets the time from GPS and stores the local offset as a number of minutes. Mine was set to 180.I changed it to 120.
That is how I was finally able to fix my car’s timezone.
↫ Rasmus Moorats
This harrowing story involved an older car – a 2014 Renault Latitude – but with the number of screens and the amount of user-facing software only increasing every year, requiring jailbreaks to get your car to do what you want it to do are only going to become more common. I wouldn’t be surprised if whole generations of cars are going to become much harder to sell in the near future, cratering the used market, because people are not willing to put up with software problems nobody wants to or can fix.
He just wanted to change the goddamn time.
