Improper Prevention of Lock Bit Modification

The product uses a trusted lock bit for restricting access to registers, address regions, or other resources, but the product does not prevent the value of the lock bit from being modified after it has been set.

Soyutlama

Base

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

Genişletilmiş açıklama

In integrated circuits and hardware intellectual property (IP) cores, 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 behavior is commonly implemented using a trusted lock bit. When set, the lock bit disables writes to a protected set of registers or address regions. Design or coding errors in the implementation of the lock bit protection feature may allow the lock bit to be modified or cleared by software after it has been set. Attackers might be able to unlock the system and features that the bit is intended to protect.

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

Registers protected by lock bit can be modified even when 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.

Etkinlik: High

Doğrulama

Nasıl tespit edilir?

Manual Analysis

High

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