At 47:10, they mention that they haven't found anything evil. Ofc, this isn't hard proof, but if I trust anyone's answer, then it's theirs. I think the likelihood of it being malicious is nonzero, but small enough that I'd condemn active backdoors into the realm of conspiracy theories.
There's always the possibility of it being exploited by others, but c'mon: Basically ANY other exploit would be way easier to distribute and activate than one in the PSP.
As much as I love speculating about backdoors and NSA wiretapping, I seriously doubt these MEs are malicious. At this point, managing a modern x86 is tough work, especially if you want to run virtualization, complex threading and maintain high efficiency. It makes total sense that there are mandatory supervisor chips at this point, and without any evidence that these chips are "phoning home," I simply have to assume that it's purpose is virtualized KVM for remote management. Worst case scenario, the CIA wakes up my laptop while I'm asleep, big whoop.
It does not even matter if they are actively malicious. They are closed, non-removable, with proven vulnerabilities (which not only CIA can use). What else do you need?
