Digitally signed updates

BR/EDR

BLE

For each update mechanism available on a device, it is necessary to verify that the updates are digitally signed. If a device accepts unsigned firmware or software, an attacker could create custom components capable of accessing data or performing malicious actions, using the device in ways not intended by the manufacturer or the user.

Description

In order to check wether updates are digitally signed, multiple techniques may be used:

• Source code review.
• Sligtly modifying random bytes of a valid update file and trying to use the modifyed software. Beware that this may result in a bricked device if the software is finnaly installed.

This control is considered satisfactory when it is verified that the device does not remotely accept minimally modified updates.