AMD CPU debug mode cracked

[hoom]

Here & here
Could this open AMD CPUs to some dangerous malware? Bit scary depending on what is actually being unlocked

Could just be a beatup of something completely innocuous though

 

[Squilliam]

It says researchers... I dunno. I'll wait for someone smarter than me in this topic pipes up. Maybe Aaron since he works / worked at Intel.

 

[pcchen]

It's unlikely a malware could benefit from this because you need ring 0 to access MSR anyway. If you have a malware running in ring 0 you're already in big trouble I'm not sure about the implication on virtualization (which is basically an extra ring -1) though.

 

[hoom]

Right, thats not so concerning then.
Would have been bad if it was a way that security levels could be bypassed.

 

[Npl]

Would be quite a big mistake if AMD secured a potential backdoor with a key that you can brute-force in seconds

probably mainly diagnostic stuff. Anyone know where the names of "undocumented" registers came from: http://cbid.softnology.biz/html/undocmsrs.html.

 

[hoom]

Security by obscurity is nothing new & hasn't magically disappeared.

 

[3dilettante]

Security through obscurity was discussed before when it came to the microcode update engines for both Intel and AMD. A compromise there could actually modify processor behavior, rather than just allow reporting of on-chip events.

It doesn't look like this particular exploit compromises that, though this event and Intel's software updates for processors shows that there are software avenues to fiddling with the hardware.