CWE-336: Same Seed in Pseudo-Random Number Generator (PRNG) | Glexia
CWE-336 (Same Seed in Pseudo-Random Number Generator (PRNG)) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK…
Glexia's Take · Automated analysis
CWE-336: Same Seed in Pseudo-Random Number Generator (PRNG)
Same Seed in Pseudo-Random Number Generator (PRNG) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Other,Access Control: Other,Bypass Protection Mechanism
Developer Pattern
CWE-336 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-336, 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-336: Same Seed in Pseudo-Random Number Generator (PRNG)
A Pseudo-Random Number Generator (PRNG) uses the same seed each time the product is initialized.
Given the deterministic nature of PRNGs, using the same seed for each initialization will lead to the same output in the same order. If an attacker can guess (or knows) the seed, then the attacker may be able to determine the random numbers that will be produced from the PRNG.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- The following code uses a statistical PRNG to generate account IDs. Because the program uses the same seed value for every invocation of the PRNG, its values are predictable, making the system vulnerable to attack.
- This code attempts to generate a unique random identifier for a user's session. Because the seed for the PRNG is always the user's ID, the session ID will always be the same. An attacker could thus predict any user's session ID and potentially hijack the session.,If the user IDs are generated sequentially, or otherwise restricted to a narrow range of values, then this example also exhibits a Small Seed Space (CWE-339).
Remediation
- Architecture and Design: Do not reuse PRNG seeds. Consider a PRNG that periodically re-seeds itself as needed from a high quality pseudo-random output, such as hardware devices.
- Architecture and Design,Requirements: 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.
Detection
- Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Mappings
Related CVEs, CWEs, and ATT&CK context
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.