CWE-337 — Predictable Seed in Pseudo-Random Number Generator (PRNG)
CWE-337: Predictable Seed in Pseudo-Random Number Generator (PRNG)
MITRE CWE weakness
| Kind | Weakness |
| Abstraction | Variant |
| Status | Draft |
| Likelihood of exploit | — |
Description
A Pseudo-Random Number Generator (PRNG) is initialized from a predictable seed, such as the process ID or system time.
The use of predictable seeds significantly reduces the number of possible seeds that an attacker would need to test in order to predict which random numbers will be generated by the PRNG.
Common consequences
- Other: Varies by Context
Mitigations
General — Use non-predictable inputs for seed generation.
Architecture and Design — Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems, or use the more recent FIPS 140-3 [REF-1192] if possible.
Implementation — Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.
References
- CWE page: https://cwe.mitre.org/data/definitions/337.html
- CWE list: https://cwe.mitre.org/data/index.html