Well, GE's engineering presentations of full system attestation and integrity analysis/measurement suddenly seem so much more relevant and scary - if those techniques are implemented in these surveillance networks. They presented this in the context of energy infrastructure - but surveillance works too I guess. It seems they've been working on software/hardware to make subverting these things much more difficult in the open for a while now:
https://lssna19.sched.com/event/RHar/tutorial-complete-platf...