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I have tried to decompile the firmware binary of a microcontroller that should be an STM32 (but I'm not sure about this).

After the analysis I get only few codelines with a lot of similar messages:

                   /* WARNING: Bad instruction - Truncating control flow here */
    halt_baddata();
  }
                    /* WARNING: Could not recover jumptable at 0x00000008. Too many branches */
                    /* WARNING: Treating indirect jump as call */
  (*(code *)(unaff_r4 ^ unaff_r4 << 0xe))();

And the strings seems meaningless bunch of chars.

I have tried also ARM aggressive instruction finder without success.

I have also tried to set base address 0x08000000 that seems common for various STM32 with analogous bad results.

I have also tried to use bot arm v7 little and big endian as trial and error.

How should I proceed considering that I don't know the datasheet of microcontroller used?

Here The File

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  • Do you have physical access to the microcontroller? Are there any serial numbers or other markings on it?
    – dingo_kinznerhook
    Sep 28, 2022 at 14:29
  • @dingo_kinznerhook I cannot access it at the moment.
    – AndreaF
    Sep 28, 2022 at 14:36
  • If it is stm mcu then binary starts with isr vector table where second entry is reset handler. Did you try to disassemble as thumb instructions?
    – Rok Tavčar
    Sep 29, 2022 at 6:31
  • @RokTavčar I'm not sure it is really an STM MCU. I haven't clear what do you mean, I tried to decompile a raw binary with the options ARM/thumb mode ARM v7. I have linked the file if someone here can give a look to suggest me the correct way to disassemble in such situation. It would be really appreciated.
    – AndreaF
    Sep 29, 2022 at 14:29
  • You can't simply throw binaries at Ghidra. You need to: 1) Read the uC manuals and get an extensive and complete understanding of its working (including the boot sequence and interrupts vectors); 2) inspect the binary to understand the format used, it is a blob of code? It's a firmware FS? It's proprietary? Where it's mapped and how? 3) Dissect code and data from metadata 4) disassemble the code. Without any of this, you can only make guesses.
    – Margaret Bloom
    Sep 30, 2022 at 15:47

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