A few days before my SSTIC presentation Récupération de la clé des firmwares radio du stm32wb55 (in french), while doing my slides, I was made aware of a new release of the FUS for the stm32wb55. And of course, the attack I was going to present 5 days later was no longer working...

This is a small blog post I would have been happy to read while searching how to find ecc collision when dealing with how to exploit a limited write to flash.

No rocket science, just a little write-up.

In this post, I will show you how I bypassed a noexec permission in a limited chrooted env.

The stm32wb55 mcu is a dual core (cortex-m4/cortex-m0) mcu with integrated wireless capabilities (ble/thread/zigbee).

The percello prc6000, also known as bcm61650 after Broadcom bought the company, is a chip used in 3g femtocells (Home-nodeB).

Here is a summary writeup of how I achieved to bypass its secure ROM to run arbitrary firmwares.

After some time spent, I've finally managed to identify the jtag pins on my MC9620 "phone".

A picture is worth a thousand words...

Found this old piece of code, written in 2013. Only needed to change hardcoded resolution of the webcam to get it working again.