ESP: Security gaps and bugs

Moderated By dondu:

Hover topic, as this is important information and would be good to be collected in one topic.

khoam wrote:

dondu wrote:

This can be understood, which will cause a problem with software substitutions to address other security vulnerabilities. I think they have backed themselves into a corner all the more

.
I suggest reading the current eFuse documentation for ESP32:
https://www.espressif.com/sites/default/files...ation/esp32_technical_reference_manual_en.pdf (chapter 20), and
https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/system/efuse.html

Quote:

The attack works against eFuse, a one-time programmable memory where data can be burned to the device. The ESP32 official documentation describes why the attack works: "Each eFuse is a one-bit field which can be programmed to 1 after which it cannot be reverted back to 0." By burning a payload into the device’s eFuse, no software update can ever reset the fuse and the chip must be physically replaced or the device discarded.

khoam wrote:

dondu wrote:

I only read the article indicated in the first post and in it:

.
Well, that's exactly what it said, but it didn't include any more information, that this requires direct physical access to the MCU in the device in question and requires "some" modifications in the pcb itself and in some cases opening the metal case ESP32, if there is one - I'm not referring to the simple and cheap developer boards from AliExpress on which "penetration" tests have been done, because that was simpler.

Furthermore, Espressif's recommendations were and are clear on ESP32 security (as long as one needs, understands and uses them):
• Use per-device unique keys for Secure Boot and Flash Encryption.
• Generate per-device unique keys stored in flash for application uses, rather than using a single shared key across all devices. .

Following the above rules ensures that 'breaking' one ESP32 in one unit of a given device, will not result in 'breaking' the security in all other ESP32s in the same devices i.e. with the same firmware. The wise will listen and the foolish will 'save'.

This is what one of the 'hacking' steps looks like after removing the ESP32's metal casing: