CWE-339: Small Seed Space in PRNG
Description
A Pseudo-Random Number Generator (PRNG) uses a relatively small seed space, which makes it more susceptible to brute force attacks.
PRNGs are entirely deterministic once seeded, so it should be extremely difficult to guess the seed. If an attacker can collect the outputs of a PRNG and then brute force the seed by trying every possibility to see which seed matches the observed output, then the attacker will know the output of any subsequent calls to the PRNG. A small seed space implies that the attacker will have far fewer possible values to try to exhaust all possibilities.
- Abstraction
- VariantA weakness tied to a specific language, technology or resource.
- Likelihood of exploit
- Not rated by MITRE
- Status
- Draft
Common consequences
- Other
Varies by Context
Potential mitigations
- Architecture and Design
Use well vetted pseudo-random number generating algorithms with adequate length seeds. Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a random enough number.
- Architecture and DesignRequirementsLibraries or Frameworks
Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems, or use the more recent FIPS 140-3 if possible.
Related weaknesses
CAPEC attack patterns that exploit it
CWE 4.20 links no CAPEC attack pattern to this weakness.