2074
Scope Impact Likelihood
Confidentiality
Integrity
Availability
Access Control
Modify Files or Directories
Execute Unauthorized Code or Commands
Bypass Protection Mechanism
Gain Privileges or Assume Identity
Modify Memory
Modify Memory
DoS: Crash, Exit, or Restart
High
Potential Mitigations
Phase: Architecture and Design
Phase: Implementation
Security Token assignment review checks for design inconsistency and common weaknesses.
Security-Token definition and programming flow is tested in both pre-silicon and post-silicon
testing.
Demonstrative Examples
Example 1:
For example, consider a system with a register for storing an AES key for encryption and
decryption. The key is of 128 bits implemented as a set of four 32-bit registers. The key register
assets have an associated control register, AES_KEY_ACCESS_POLICY, which provides the
necessary access controls. This access-policy register defines which agents may engage in a
transaction, and the type of transaction, with the AES-key registers. Each bit in this 32-bit register
defines a security Token. There could be a maximum of 32 security Tokens that are allowed
access to the AES-key registers. The number of the bit when set (i.e., "1") allows respective action
from an agent whose identity matches the number of the bit and, if "0" (i.e., Clear), disallows the
respective action to that corresponding agent.
Let's assume the system has two agents: a Main-controller and an Aux-controller. The respective
Security Tokens are "1" and "2".
An agent with Security Token "1" has access to AES_ENC_DEC_KEY_0 through
AES_ENC_DEC_KEY_3 registers. As per the above access policy, the AES-Key-access policy
allows access to the AES-key registers if the security Token is "1".
Example Language: Other (Bad)
The Aux-controller could program its Security Token to "1" from "2".
The SoC does not properly protect the Security Token of the agents, and, hence, the Aux-controller
in the above example can spoof the transaction (i.e., send the transaction as if it is coming from the
Main-controller to access the AES-Key registers)
Example Language: Other (Good)
The SoC needs to protect the Security Tokens. None of the agents in the SoC should have the ability to change the Security
Token.
MemberOf Relationships
This MemberOf relationships table shows additional CWE Catgeories and Views that reference this
weakness as a member. This information is often useful in understanding where a weakness fits
within the context of external information sources.
Nature Type ID Name Page
MemberOf 1396 Comprehensive Categorization: Access Control 1400 2519
Notes
CWE Version 4.14
CWE-1260: Improper Handling of Overlap Between Protected Memory Ranges
CWE-1260: Improper Handling of Overlap Between Protected Memory Ranges