# Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) (CWE-338)

The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.

**Stack:** JavaScript

- Prevalence: High Frequently exploited
- Impact: High 2 high-severity rules
- Prevention: Documented 4 fix examples

**OWASP:** Cryptographic Failures (A02:2021-Cryptographic Failures) - #2

## Description

When a non-cryptographic PRNG is used in a security context (such as generating session tokens or cryptographic keys), an attacker may be able to predict its output and compromise the security mechanism.

## Prevention

Prevention strategies for Weak PRNG based on 1 Shoulder detection rules.

### Key Practices

- Use of Math

### JavaScript

Use crypto.randomBytes() or crypto.randomUUID() for security-sensitive random values

## Warning Signs

- [HIGH] Math.random() used for security-sensitive operation: ...
- [HIGH] use of Math

## Consequences

- Bypass Protection Mechanism
- Gain Privileges

## Mitigations

- Use cryptographically secure random number generators (CSPRNGs)
- In JavaScript, use crypto.getRandomValues() or crypto.randomUUID()
- In Python, use secrets module instead of random

## Detection

- Total rules: 4
- Languages: go, javascript, typescript, python

## Rules by Language

### Javascript (1 rules)

- **Weak Random Number Generation in Security Context** [HIGH]: Detects use of Math.random() for security-sensitive operations like generating
tokens, session IDs, or cryptographic keys. Math.random() is not cryptographically
secure and can be predicted by attackers.
  - Remediation: Replace Math.random() with cryptographically secure alternatives.

### Typescript (1 rules)

- **Weak Random Number Generation in Security Context** [HIGH]: Detects use of Math.random() for security-sensitive operations like generating
tokens, session IDs, or cryptographic keys. Math.random() is not cryptographically
secure and can be predicted by attackers.
  - Remediation: Replace Math.random() with cryptographically secure alternatives.