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

[MSipo]

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.

[Tesla DeLorean]

>>But how safe is it?

Not very

[Uwe Bonnes]

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

[MSipo]

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?

[Tesla DeLorean]

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

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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.

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