COMMON WEAKNESS ENUMERATIONIncomplete

CWE-1290

Incorrect Decoding of Security Identifiers

The product implements a decoding mechanism to decode certain bus-transaction signals to security identifiers. If the decoding is implemented incorrectly, then untrusted agents can now gain unauthorized access to the asset.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product implements a decoding mechanism to decode certain bus-transaction signals to security identifiers. If the decoding is implemented incorrectly, then untrusted agents can now gain unauthorized access to the asset.

Extended description

In a System-On-Chip (SoC), various integrated circuits and hardware engines generate transactions such as to access (reads/writes) assets or perform certain actions (e.g., reset, fetch, compute, etc.). Among various types of message information, a typical transaction is comprised of source identity (to identify the originator of the transaction) and a destination identity (to route the transaction to the respective entity). Sometimes the transactions are qualified with a security identifier. The security identifier helps the destination agent decide on the set of allowed actions (e.g., access an asset for read and writes). A decoder decodes the bus transactions to map security identifiers into necessary access-controls/protections. A common weakness that can exist in this scenario is incorrect decoding because an untrusted agent's security identifier is decoded into a trusted agent's security identifier. Thus, an untrusted agent previously without access to an asset can now gain access to the asset.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

Lifecycle phase

Architecture and Design

Risk

What does successful exploitation lead to?

Modify MemoryRead MemoryDoS: Resource Consumption (Other)Execute Unauthorized Code or CommandsGain Privileges or Assume IdentityQuality Degradation

Affected security scopes: Confidentiality, Integrity, Availability, Access Control

Defence

How is it prevented and fixed?

Architecture and Design

Architecture and design approach

Detail
Security identifier decoders must be reviewed for design consistency and common weaknesses.

Implementation

Implementation-phase defence

Detail
Access and programming flows must be tested in pre-silicon and post-silicon testing in order to check for this weakness.