CWE-1267: Policy Uses Obsolete Encoding

MITRE CWE weakness

Description

The product uses an obsolete encoding mechanism to implement access controls.

Within a System-On-a-Chip (SoC), various circuits and hardware engines generate transactions for the purpose of accessing (read/write) assets or performing various actions (e.g., reset, fetch, compute, etc.). Among various types of message information, a typical transaction is comprised of source identity (identifying the originator of the transaction) and a destination identity (routing the transaction to the respective entity). Sometimes the transactions are qualified with a Security Token. This Security Token helps the destination agent decide on the set of allowed actions (e.g., access to an asset for reads and writes). A policy encoder is used to map the bus transactions to Security Tokens that in turn are used as access-controls/protection mechanisms. A common weakness involves using an encoding which is no longer trusted, i.e., an obsolete encoding.

Common consequences

• Confidentiality, Integrity, Availability, Access Control: Modify Memory, Read Memory, Modify Files or Directories, Read Files or Directories, DoS: Resource Consumption (Other), Execute Unauthorized Code or Commands, Gain Privileges or Assume Identity, Bypass Protection Mechanism, Reduce Reliability

Mitigations

Architecture and Design — Security Token Decoders should be reviewed for design inconsistency and common weaknesses. Access and programming flows should be tested in both pre-silicon and post-silicon testing.

References

• CWE page: https://cwe.mitre.org/data/definitions/1267.html
• CWE list: https://cwe.mitre.org/data/index.html