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bsuthar
Associate III
May 6, 2026
Question

Most Secure STM32 ?

  • May 6, 2026
  • 2 replies
  • 279 views

Hello Team,

Good Day !

After Cloneed our two version of Hardware ( STM32F3 Series based ) by compititor , we are now more focused on Hardware Security aspects.

Can you Pls Suggest which STM32 MCU is the MOST Secure among all available MCU ? Considering Firmware Protection / physical  Attacks ? 

I would appriciate , if Higher Level Architecture with Device name is Provided.

We are also open for Paid Consultancy if any 3rd party ready to help...

 

Regards ,

Bhupendra

2 replies

Bubbles
Bubbles
ST Employee
May 6, 2026

Hello @bsuthar ,

I'd suggest to try the reading the Introduction to security for STM32 MCUs - Application note first. The AN also includes tables comparing the security features found in different STM32 series.

Of the series on the market, I'd probably suggest the STM32H5 (crypto line) as the most secure. But the security is only working if the application uses all the security features correctly. 

BR,

J

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    B
    bsutharAuthor
    Associate III
    May 7, 2026

    Yes, @Bubbles 

    we had gone through this Docs and belive firmware extraction done through "Semi-Invasive Method" , for STM32F3 series MCU. 

    Bubbles
    Bubbles
    ST Employee
    May 11, 2026

    Hi @bsuthar,

    the RDP1 alone is not really an obstacle for determined attacker and only provides false sense of security. We are even dropping it from some of our newer products (STM32C5 for example). It can still be quite effective when combined with other protections like boot lock.

    The main problem of RDP2 on older product was that regression was impossible in case of field return. With newer STM32 series, starting with STM32U5, the regression may be conditional to a secret passcode known only be the manufacturer. The STM32H5 may have the regression even protected cryptographically. This way there's no excuse not to deploy the product without (RDP2/closed) protection.

    Still, it's better to combine even the RDP2 with boot lock, HDP and other protections available.

    BR,

    J

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      Pavel A.
      Pavel A.
      Super User
      May 7, 2026

      > We are also open for Paid Consultancy if any 3rd party ready to help...

      Could you tell what is the kind of your device, so relevant experts could join?

      For example: motor or drone controller? Industrial controller? Consumer, musical, game/toy? etc.

       

      B
      bsutharAuthor
      Associate III
      May 7, 2026

      @Pavel A. 

      yes , it is Industrial Motion controller.

      Currently , It is based on STM32F303 Device. 
      Unfortunately , It is clonned Two times ( along with Firmware). 

      Last HW Version had Following Feature : 

      ------------------------------------------------------------

      1. Custom BootLoader (WRP ON)

      2. CRC Checksum check for Application Firmware (RoT) Authentication on Startup

      3. RDP1

      4. USB Communication Encrypted (Asymmetric)

      --------------------------------------------------------------------------------

      Ozone
      Ozone
      Principal
      May 7, 2026

      > 3. RDP1

      Perhaps this is not sufficient.
      An attacker could boot from System ROM, inject code into RAM, and thus break your protection.

      Perhaps you are aware of Ghidra or similiar software packages : https://github.com/NationalSecurityAgency/ghidra
      With such tools, you can easily convert binary code back into readable C code (without original variable names, of course).

      Or, in the simplest case, the attacker just reads out the Flash into a file, and flashes it onto his clones.

      While I have only superficial knowledge of this topic and scene, I would check out the size of the cloning competitors (financial & product output). For small ones, I would suspect minimal-effort cloning (i.e. the second, simpler case).
      RDP level 2 might be too much of hurdle for those.

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