CWE-1241: Use of Predictable Algorithm in Random Number… | Glexia
CWE-1241 (Use of Predictable Algorithm in Random Number Generator) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE…
Glexia's Take · Automated analysis
CWE-1241: Use of Predictable Algorithm in Random Number Generator
Use of Predictable Algorithm in Random Number Generator represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Confidentiality: Read Application Data
Developer Pattern
CWE-1241 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-1241, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-1241: Use of Predictable Algorithm in Random Number Generator
The device uses an algorithm that is predictable and generates a pseudo-random number.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Suppose a cryptographic function expects random value to be supplied for the crypto algorithm. During the implementation phase, due to space constraint, a cryptographically secure random-number-generator could not be used, and instead of using a TRNG (True Random Number Generator), a LFSR (Linear Feedback Shift Register) is used to generate a random value. While an LFSR will provide a pseudo-random number, its entropy (measure of randomness) is insufficient for a cryptographic algorithm.
- The example code is taken from the PRNG inside the buggy OpenPiton SoC of HACK@DAC'21 [REF-1370]. The SoC implements a pseudo-random number generator using a Linear Feedback Shift Register (LFSR). , ,A LFSR's input bit is determined by the output of a linear function of two or more of its previous states. Therefore, given a long cycle, a LFSR-based PRNG will enter a repeating cycle, which is predictable.
Remediation
- Architecture and Design: It is highly recommended to use a true random number generator (TRNG) to ensure the security of encryption schemes. Hardware-based TRNGs generate unpredictable, unbiased, and independent random numbers because they employ physical phenomena, e.g., electrical noise, as sources to generate random numbers.
- Implementation: It is highly recommended to use a true random number generator (TRNG) to ensure the security of encryption schemes. Hardware-based TRNGs generate unpredictable, unbiased, and independent random numbers because they employ physical phenomena, e.g., electrical noise, as sources to generate random numbers.
Detection
- Code review
- SAST
- DAST
- Focused regression tests
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.