CWE-1248 Semiconductor Defects in Hardware Logic with Security-Sensitive Implications

The security-sensitive hardware module contains semiconductor defects.

• Availability, Access Control: DoS: Instability — Semiconductor defects manifest as faults on chip-internal signals or registers, have the effect of inputs, outputs, or intermediate signals being always 0 or always 1, and do not switch as expected. If such faults occur in security-sensitive hardware modules, the security objectives of the hardware module may be compromised.

• [Testing] While semiconductor-manufacturing companies implement several mechanisms to continuously improve the semiconductor manufacturing process to ensure reduction of defects, some defects can only be fixed after manufacturing. Post-manufacturing testing of silicon die is critical. Fault models such as stuck-at-0 or stuck-at-1 must be used to develop post-manufacturing test cases and achieve good coverage. Once the silicon packaging is done, extensive post-silicon testing must be performed to ensure that hardware logic implementing security functionalities is defect-free. • [Operation] Operating the hardware outside device specification, such as at extremely high temperatures, voltage, etc., accelerates semiconductor degradation and results in defects. When these defects manifest as faults in security-critical, hardware modules, it results in compromise of security guarantees. Thus, operating the device within the specification is important.