detail
The update endpoint checked a CRC and nothing else. We wrote an image that kept the device fully functional, unlocked a nominated door on a schedule, and survived a factory reset.
The vendor shipped signed updates in 2.9 for current models. Two discontinued models remain unfixed and are still widely deployed. If you operate them, the only reliable mitigation is network isolation of the management interface.
We are publishing this in full because the affected devices are physically accessible in public buildings and the mitigation is entirely within an operator's control.
