COMMON WEAKNESS ENUMERATIONIncomplete

CWE-1209

Failure to Disable Reserved Bits

The reserved bits in a hardware design are not disabled prior to production. Typically, reserved bits are used for future capabilities and should not support any functional logic in the design. However, designers might covertly use these bits to debug or further develop new capabilities in production hardware. Adversaries with access to these bits will write to them in hopes of compromising hardware state.

Soyutlama

Base

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

The reserved bits in a hardware design are not disabled prior to production. Typically, reserved bits are used for future capabilities and should not support any functional logic in the design. However, designers might covertly use these bits to debug or further develop new capabilities in production hardware. Adversaries with access to these bits will write to them in hopes of compromising hardware state.

Genişletilmiş açıklama

Reserved bits are labeled as such so they can be allocated for a later purpose. They are not to do anything in the current design. However, designers might want to use these bits to debug or control/configure a future capability to help minimize time to market (TTM). If the logic being controlled by these bits is still enabled in production, an adversary could use the logic to induce unwanted/unsupported behavior in the hardware.

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Architecture and Design

The Designer and Implementer have to make a conscious choice to do this.

Yaşam döngüsü evresi

Implementation

The Designer and Implementer have to make a conscious choice to do this.

Yaşam döngüsü evresi

Documentation

If documentation labels anything "for future use", "reserved", or the like, such labeling could indicate to an attacker a potential attack point.

Risk

Başarılı sömürü neye yol açar?

Varies by Context

Etkilenen güvenlik alanları: Confidentiality, Integrity, Availability, Access Control, Accountability, Authentication, Authorization, Non-Repudiation

This type of weakness all depends on the capabilities of the logic being controlled or configured by the reserved bits.

Savunma

Nasıl önlenir ve çözülür?

Architecture and Design · Implementation

Birden fazla yaşam döngüsü evresinde uygulanacak savunma

Detay
Include a feature to disable reserved bits.

Integration

Integration aşaması savunması

Detay
Any writes to these reserve bits are blocked (e.g., ignored, access-protected, etc.), or an exception can be asserted.