Missing Cryptographic Step
Draft Base
Structure: Simple
Description
The product does not implement a required step in a cryptographic algorithm, resulting in weaker encryption than advertised by the algorithm.
Common Consequences 3
Scope: Access Control
Impact: Bypass Protection Mechanism
Scope: ConfidentialityIntegrity
Impact: Read Application DataModify Application Data
Scope: AccountabilityNon-Repudiation
Impact: Hide Activities
Demonstrative Examples 1
The example code is taken from the HMAC engine inside the buggy OpenPiton SoC of HACK@DAC'21 [REF-1358]. HAMC is a message authentication code (MAC) that uses both a hash and a secret crypto key. The HMAC engine in HACK@DAC SoC uses the SHA-256 module for the calculation of the HMAC for 512 bits messages.
Code Example:
Bad
Verilog
logic [511:0] bigData; ...
hmac hmac(
verilog.message_i(bigData),** .hash_o(hash), .ready_o(ready), .hash_valid_o(hashValid)
However, this HMAC engine cannot handle messages that are longer than 512 bits. Moreover, a complete HMAC will contain an iterate hash function that breaks up a message into blocks of a fixed size and iterates over them with a compression function (e.g., SHA-256). Therefore, the implementation of the HMAC in OpenPiton SoC is incomplete. Such HMAC engines will not be used in real-world applications as the messages will usually be longer than 512 bits. For instance, OpenTitan offers a comprehensive HMAC implementation that utilizes a FIFO for temporarily storing the truncated message, as detailed in [REF-1359].
To mitigate this, implement the iterative function to break up a message into blocks of a fixed size.
Observed Examples 1
CVE-2001-1585Missing challenge-response step allows authentication bypass using public key.
References 2
hmac_wrapper.sv
2021
ID: REF-1358
Applicable Platforms
Languages:
Not Language-Specific : Undetermined
Technologies:
Not Technology-Specific : Undetermined
Modes of Introduction
Implementation
Requirements
Related Attack Patterns
Functional Areas
- Cryptography
Related Weaknesses
Taxonomy Mapping
- PLOVER
- OWASP Top Ten 2007
- OWASP Top Ten 2007
Notes
RelationshipOverlaps incomplete/missing security check.
RelationshipCan be resultant.