CWE-338 — Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
MITRE CWE weakness
| Kind | Weakness |
| Abstraction | Base |
| Status | Draft |
| Likelihood of exploit | Medium |
Description
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.
When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.
Common consequences
- Access Control: Bypass Protection Mechanism
Mitigations
Implementation — Use functions or hardware which use a hardware-based random number generation for all crypto. This is the recommended solution. Use CyptGenRandom on Windows, or hw_rand() on Linux.
References
- CWE page: https://cwe.mitre.org/data/definitions/338.html
- CWE list: https://cwe.mitre.org/data/index.html