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Comment by ChuckNorris89 | Hacker News Reader

Could a hack be possible by exploiting the GPU? Like making a 3D game scene that's actually encoding malware so when the GPU tries to render it you now have access to the system resources?

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Don't know about a scene, but EC2-like access to virtual GPUs was rumored to be pretty dangerous, potentially even to the hardware itself (think something like changing the voltages via undocumented registers). The attack surface there is enormous. It was rumors, maybe someone here knows better.

You can target co-processors in general, e.g., here [1], thus I assume people do hack GPUs.

Generally, the better we become in introducing mitigations, the more expensive attacks become and attackers have bosses, budgets and deadlines. They will try to find other avenues to land on a target :-)

[1]https://objectivebythesea.org/v5/talks/OBTS_v5_iBeer.pdf

We do read about occasional vulnerabilities on phone GPUs, but I do have to wonder. Wouldn't the compartmentalization and difference in compute abilities between CPU and GPU inherently limit the scope to which a vulnerability on the GPU in a typical PC can exploit?

Compartmentalization might make chaining the exploit more difficult, but it's certainly not unheard of. There have been exploit chains in the past that manage to jump from the baseband to the main CPU, for example.

One of my favorite exploits [0] was from Project Zero where the chain began with a vulnerability in the Apple wireless stack (Broadcom? maybe, but that might be a different exploit I'm thinking of), and ended in arbitrary kernel RCE. In other words, it was "a wormable radio-proximity exploit which allows me to gain complete control over any iPhone in my vicinity."

More relevantly to your question, here's a writeup about exploiting a GPU. [1]

[0] https://googleprojectzero.blogspot.com/2020/12/an-ios-zero-c...

[1] https://googleprojectzero.blogspot.com/2020/09/attacking-qua...

Thank you! Not my area but I do love reading about it.

Same... the people at Project Zero are basically magicians. I love reading their write-ups, even if I barely understand most of them.

Generally, no. Often you’ll see GPUs have extensive access to the system’s physical memory and vice versa which makes exploiting either processor from the other fairly common due to buggy drivers.

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