CWE-1234: Hardware Internal or Debug Modes Allow Override of Locks

MITRE CWE weakness

Description

System configuration protection may be bypassed during debug mode.

Device configuration controls are commonly programmed after a device power reset by a trusted firmware or software module (e.g., BIOS/bootloader) and then locked from any further modification. This is commonly implemented using a trusted lock bit, which when set, disables writes to a protected set of registers or address regions. The lock protection is intended to prevent modification of certain system configuration (e.g., memory/memory protection unit configuration). If debug features supported by hardware or internal modes/system states are supported in the hardware design, modification of the lock protection may be allowed allowing access and modification of configuration information.

Common consequences

• Access Control: Bypass Protection Mechanism

Mitigations

Architecture and Design — Security Lock bit protections should be reviewed for any bypass/override modes supported. Any supported override modes either should be removed or protected using authenticated debug modes. Security lock programming flow and lock properties should be tested in pre-silicon and post-silicon testing.

References

• CWE page: https://cwe.mitre.org/data/definitions/1234.html
• CWE list: https://cwe.mitre.org/data/index.html