CWE-332: Insufficient Entropy in PRNG
The lack of entropy available for, or used by, a Pseudo-Random Number Generator (PRNG) can be a stability and security threat.
How it's found
Insufficient Entropy in PRNG is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
Consequences
- DoS: Crash, Exit, or Restart: If a pseudo-random number generator is using a limited entropy source which runs out (if the generator fails closed), the program may pause or crash.
- Bypass Protection Mechanism, Other: If a PRNG is using a limited entropy source which runs out, and the generator fails open, the generator could produce predictable random numbers. Potentially a weak source of random numbers could weaken the encryption method used for authentication of users.
Mitigations
- Architecture and Design/Requirements: Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems. Consult FIPS 140-2 Annex C ("Approved Random Number Generators").
- Implementation: Consider a PRNG that re-seeds itself as needed from high-quality pseudo-random output, such as hardware devices.
- Architecture and Design: When deciding which PRNG to use, look at its sources of entropy. Depending on what your security needs are, you may need to use a random number generator that always uses strong random data -- i.e., a random number generator that attempts to be strong but will fail in a weak way or will always provide some middle ground of protection through techniques like re-seeding. Generally, something that always provides a predictable amount of strength is preferable.
Where this fits in a TurboPentest engagement
TurboPentest's agentic pentest is powerful and covers a broad range of issues automatically. This particular class is best confirmed in a manual IntegSec engagement, where human pentesters apply deeper methodology and a larger context window than any automated pass.
Frequently asked questions
What is CWE-332?
The lack of entropy available for, or used by, a Pseudo-Random Number Generator (PRNG) can be a stability and security threat.
How do you find Insufficient Entropy in PRNG?
Insufficient Entropy in PRNG is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
What is the impact of CWE-332?
DoS: Crash, Exit, or Restart: If a pseudo-random number generator is using a limited entropy source which runs out (if the generator fails closed), the program may pause or crash. Bypass Protection Mechanism, Other: If a PRNG is using a limited entropy source which runs out, and the generator fails open, the generator could produce predictable random numbers. Potentially a weak source of random numbers could weaken the encryption method used for authentication of users.
Does TurboPentest test for Insufficient Entropy in PRNG?
TurboPentest's agentic pentest is powerful and covers a broad range of issues automatically. This particular class is best confirmed in a manual IntegSec engagement, where human pentesters apply deeper methodology and a larger context window than any automated pass.
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