Security-Sensitive Hardware Controls with Missing Lock Bit Protection

The product uses a register lock bit protection mechanism, but it does not ensure that the lock bit prevents modification of system registers or controls that perform changes to important hardware system configuration.

Soyutlama

Base

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

Genişletilmiş açıklama

Integrated circuits and hardware intellectual properties (IPs) might provide device configuration controls that need to be programmed after device power reset by a trusted firmware or software module, commonly set by BIOS/bootloader. After reset, there can be an expectation that the controls cannot be used to perform any further modification. This behavior is commonly implemented using a trusted lock bit, which can be set to disable 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). However, if the lock bit does not effectively write-protect all system registers or controls that could modify the protected system configuration, then an adversary may be able to use software to access the registers/controls and modify the protected hardware configuration.

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Architecture and Design

Such issues could be introduced during hardware architecture and design and identified later during Testing or System Configuration phases.

Yaşam döngüsü evresi

Implementation

Such issues could be introduced during implementation and identified later during Testing or System Configuration phases.

Risk

Başarılı sömürü neye yol açar?

Modify Memory

Etkilenen güvenlik alanları: Access Control

System Configuration protected by the lock bit can be modified even when the lock is set.

Savunma

Nasıl önlenir ve çözülür?

Architecture and Design · Implementation · Testing

Birden fazla yaşam döngüsü evresinde uygulanacak savunma

Detay

- Security lock bit protections must be reviewed for design inconsistency and common weaknesses. - Security lock programming flow and lock properties must be tested in pre-silicon and post-silicon testing.

Doğrulama

Nasıl tespit edilir?

Manual Analysis

High

Set the lock bit. Attempt to modify the information protected by the lock bit. If the information is changed, implement a design fix. Retest. Also, attempt to indirectly clear the lock bit or bypass it.