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Change all JTAG pins to inputs to prevent read out of RAM?

MSipo
Senior II

How safe is it to change all JTAG pins to inputs to prevent read out of RAM in protection level 1?

I tried it today and I could no longer connect to the board and dump the RAM. But how safe is it?

I read about the Nintendo Game & Watch that use an STM32H7B0. They were able to hack the ROM loading by dumping the STM32 RAM.

I wan't to make it harder for hackers to dump my RAM. Else I must go to protection level 2.

1 ACCEPTED SOLUTION

Accepted Solutions

Resets typically don't clear RAM, although that is often done by startup code.

The real issue is that the adversary is more smart, has more time, is more tenacious, is better equipped/resourced​, and only has to find the weakest point to make entry.

Script Kidz and paint by numbers devs aren't hard to confuse, but they also aren't the real threat.​

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View solution in original post

4 REPLIES 4

>>But how safe is it?

Not very

Tips, buy me a coffee, or three.. PayPal Venmo Up vote any posts that you find helpful, it shows what's working..
Uwe Bonnes
Principal II

If NRST is available, connect under reset will still allow to attach via the SWJ pins.

Yes. But it would not allow a "hot plug" (I think) and dump of RAM. I could not hot plug with ST link utility when I tried it.

No problems if they need to connect during reset as this will also reset the RAM contents, so that way a hacker can't dump my RAM?

Resets typically don't clear RAM, although that is often done by startup code.

The real issue is that the adversary is more smart, has more time, is more tenacious, is better equipped/resourced​, and only has to find the weakest point to make entry.

Script Kidz and paint by numbers devs aren't hard to confuse, but they also aren't the real threat.​

Tips, buy me a coffee, or three.. PayPal Venmo Up vote any posts that you find helpful, it shows what's working..