Weakness · Medium
CWE-342: Predictable Exact Value from Previous Values
What it is
An exact value or random number can be precisely predicted by observing previous values.
- Severity (our rating)
- Medium
- Likelihood of exploit
- Not rated by MITRE
- Introduced during
- Architecture and Design, Implementation
- Exploited in the wild
- No CVE in CISA's catalog
What an attacker can do
- Varies by Context (Other)
How to prevent it
General
- Increase the entropy used to seed a PRNG.
Architecture and Design
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems. Consult FIPS 140-2 Annex C ("Approved Random Number Generators").
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.
H2 Security
Found it in your code?
We review where it appears, fix it with your team, and check it was not already used against you.
Talk to our teamT Academy
Stop writing it in the first place
Learn to build software and systems without weaknesses like this one, with practice on real hosts in your browser, every objective checked on the machine.
Start freeSource: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.