4 ms·

I'd argue that a factory backdoored RNG would be infinitely more dangerous. An AMT exploit wouldn't be passive, and it wouldn't weaken every crypto operation p

by woodman 10y ago

I'd argue that a factory backdoored RNG would be infinitely more dangerous. An AMT exploit wouldn't be passive, and it wouldn't weaken every crypto operation proceeding the time of the attack. Between the two, which do you think an entity with a massive surveillance network, and a history of intentionally weakening security infrastructure, would prefer?

nickpsecurity 10y ago
An AMT exploit, if having internal access to CPU, could weaken a RNG plus anything else you can think of. Passive attacks are definitely possible with a backdoor. It just makes a component, hardware or software, do something upon certain trigger conditions. Otherwise it stays silent. Example from high-assurance field: https://calhoun.nps.edu/bitstream/handle/10945/6073/02Mar_AndersonE.pdf;sequence=1 https://calhoun.nps.edu/bitstream/handle/10945/6073/02Mar_An...
- spydum 10y ago
  I think woodmans argument is that AMT is an active service, you should see network traffic to the management engine and such -- so firewalls/airgaps/SPI should detect and prevent tampering. I think that is a naive view of AMT, it seems far more capable, network management is just one avenue (and it's been proven difficult to comprehensively implement anyways).
  - nickpsecurity 10y ago
    Ahh. I think the hardware parts of my write-up on smartphone risks will help here: https://news.ycombinator.com/item?id=10906999 https://news.ycombinator.com/item?id=10906999 Basically, modern SOC's are mixed-signal systems that have digital, analog, and often RF capabilities. I've imagined, with limited HW knowledge, quite a few attacks on digital subsystems using analog or RF components. HW gurus I know encounter sneaky stuff like that in 3rd party I.P. regularly and have to mitigate it. Most people have no clue it exists. They're mitigating at the networking channel which is a mere abstraction for more complex stuff going on in chip and interface point. You could even embed a radio in the sucker that turned on when it detected a certain signal in a packet header that NIDS certainly wasn't analyzing. Note that NSA TAO catalog includes active attacks with radars that rely on physical materials in counterfeit parts and SOC's with embedded radios hidden in USB connectors. Quite a few attacks at SOC level software people will never see coming.
  - woodman 10y ago
    > ...so firewalls/airgaps/SPI should detect and prevent tampering. I think that is a naive view of AMT... Nope, I'm talking about scale. You'd need to signal (paint with radar, send a packet, dip the power in morse code, put the magic cookie in the root DNS server response, whatever) every target at least once prior to exploitation. But yes, stealth would certainly be a concern that would reduce the value of AMT relative to a factory backdoored RNG.
- woodman 10y ago
  I'm not saying that AMT is no big deal, I'm saying that an intentionally weakened RNG is pretty much the worst thing ever. All crypto prior to targeting would be vulnerable: tor, bitcoin, pgp - for every machine leaving the factory with an Intel chip hosting badRNG v0.89 (depending on OS utilization).

by woodman 10y ago

nickpsecurity 10y ago

An AMT exploit, if having internal access to CPU, could weaken a RNG plus anything else you can think of. Passive attacks are definitely possible with a backdoor. It just makes a component, hardware or software, do something upon certain trigger conditions. Otherwise it stays silent. Example from high-assurance field: https://calhoun.nps.edu/bitstream/handle/10945/6073/02Mar_AndersonE.pdf;sequence=1 https://calhoun.nps.edu/bitstream/handle/10945/6073/02Mar_An...

spydum 10y ago
I think woodmans argument is that AMT is an active service, you should see network traffic to the management engine and such -- so firewalls/airgaps/SPI should detect and prevent tampering. I think that is a naive view of AMT, it seems far more capable, network management is just one avenue (and it's been proven difficult to comprehensively implement anyways).
- nickpsecurity 10y ago
  Ahh. I think the hardware parts of my write-up on smartphone risks will help here: https://news.ycombinator.com/item?id=10906999 https://news.ycombinator.com/item?id=10906999 Basically, modern SOC's are mixed-signal systems that have digital, analog, and often RF capabilities. I've imagined, with limited HW knowledge, quite a few attacks on digital subsystems using analog or RF components. HW gurus I know encounter sneaky stuff like that in 3rd party I.P. regularly and have to mitigate it. Most people have no clue it exists. They're mitigating at the networking channel which is a mere abstraction for more complex stuff going on in chip and interface point. You could even embed a radio in the sucker that turned on when it detected a certain signal in a packet header that NIDS certainly wasn't analyzing. Note that NSA TAO catalog includes active attacks with radars that rely on physical materials in counterfeit parts and SOC's with embedded radios hidden in USB connectors. Quite a few attacks at SOC level software people will never see coming.
- woodman 10y ago
  > ...so firewalls/airgaps/SPI should detect and prevent tampering. I think that is a naive view of AMT... Nope, I'm talking about scale. You'd need to signal (paint with radar, send a packet, dip the power in morse code, put the magic cookie in the root DNS server response, whatever) every target at least once prior to exploitation. But yes, stealth would certainly be a concern that would reduce the value of AMT relative to a factory backdoored RNG.
woodman 10y ago
I'm not saying that AMT is no big deal, I'm saying that an intentionally weakened RNG is pretty much the worst thing ever. All crypto prior to targeting would be vulnerable: tor, bitcoin, pgp - for every machine leaving the factory with an Intel chip hosting badRNG v0.89 (depending on OS utilization).