3 ms·

While simplicity of design can engender trust, in this case it's the stuff around it that still needs complexity. Besides, people have already demonstrated sin

While simplicity of design can engender trust, in this case it's the stuff around it that still needs complexity. Besides, people have already demonstrated single-gate backdoors that don't show up in most IC die photos.

jedimastert 6y ago
> Besides, people have already demonstrated single-gate backdoors that don't show up in most IC die photos. Source? Not that I don't believe you, but the idea sounds fascinating
- tooltower 6y ago
  Here's one that I know of: "A2: Analog Malicious Hardware" (2016) https://www.researchgate.net/profile/Kaiyuan_Yang5/publication/306301849_A2_Analog_Malicious_Hardware/links/5cce6b53458515712e928b3e/A2-Analog-Malicious-Hardware.pdf https://www.researchgate.net/profile/Kaiyuan_Yang5/publicati... Abstract: > While the move to smaller transistors has been a boon for performance it has dramatically increased the cost to fabricate chips using those smaller transistors. This forces the vast majority of chip design companies to trust a third party -- often overseas -- to fabricate their design. To guard against shipping chips with errors (intentional or otherwise) chip design companies rely on post-fabrication testing. Unfortunately, this type of testing leaves the door open to malicious modifications since attackers can craft attack triggers requiring a sequence of unlikely events, which will never be encountered by even the most diligent tester. In this paper, we show how a fabrication-time attacker can leverage analog circuits to create a hardware attack that is small (i.e., requires as little as one gate) and stealthy (i.e., requires an unlikely trigger sequence before effecting a chip's functionality). In the open spaces of an already placed and routed design, we construct a circuit that uses capacitors to siphon charge from nearby wires as they transition between digital values. When the capacitors fully charge, they deploy an attack that forces a victim flip-flop to a desired value. We weaponize this attack into a remotely-controllable privilege escalation by attaching the capacitor to a wire controllable and by selecting a victim flip-flop that holds the privilege bit for our processor. We implement this attack in an OR1200 processor and fabricate a chip. Experimental results show that our attacks work, show that our attacks elude activation by a diverse set of benchmarks, and suggest that our attacks evade known defenses.

jedimastert 6y ago

> Besides, people have already demonstrated single-gate backdoors that don't show up in most IC die photos. Source? Not that I don't believe you, but the idea sounds fascinating

tooltower 6y ago
Here's one that I know of: "A2: Analog Malicious Hardware" (2016) https://www.researchgate.net/profile/Kaiyuan_Yang5/publication/306301849_A2_Analog_Malicious_Hardware/links/5cce6b53458515712e928b3e/A2-Analog-Malicious-Hardware.pdf https://www.researchgate.net/profile/Kaiyuan_Yang5/publicati... Abstract: > While the move to smaller transistors has been a boon for performance it has dramatically increased the cost to fabricate chips using those smaller transistors. This forces the vast majority of chip design companies to trust a third party -- often overseas -- to fabricate their design. To guard against shipping chips with errors (intentional or otherwise) chip design companies rely on post-fabrication testing. Unfortunately, this type of testing leaves the door open to malicious modifications since attackers can craft attack triggers requiring a sequence of unlikely events, which will never be encountered by even the most diligent tester. In this paper, we show how a fabrication-time attacker can leverage analog circuits to create a hardware attack that is small (i.e., requires as little as one gate) and stealthy (i.e., requires an unlikely trigger sequence before effecting a chip's functionality). In the open spaces of an already placed and routed design, we construct a circuit that uses capacitors to siphon charge from nearby wires as they transition between digital values. When the capacitors fully charge, they deploy an attack that forces a victim flip-flop to a desired value. We weaponize this attack into a remotely-controllable privilege escalation by attaching the capacitor to a wire controllable and by selecting a victim flip-flop that holds the privilege bit for our processor. We implement this attack in an OR1200 processor and fabricate a chip. Experimental results show that our attacks work, show that our attacks elude activation by a diverse set of benchmarks, and suggest that our attacks evade known defenses.