CWE-331 (信息熵不充分) — Vulnerability Class 63

CWE-331 represents a cryptographic weakness where an algorithm generates insufficient entropy, resulting in predictable patterns or clusters of values rather than true randomness. This flaw is typically exploited by attackers who analyze the output to identify statistical biases, allowing them to predict future keys or session tokens with significantly higher probability than chance. By compromising the unpredictability of security mechanisms, adversaries can bypass authentication, decrypt sensitive data, or forge identities. To avoid this vulnerability, developers must ensure their random number generators are seeded with high-quality entropy sources, such as hardware-based noise generators or operating system-provided secure random functions. Relying on deterministic algorithms or low-entropy inputs like timestamps alone is insufficient; instead, implementing cryptographically secure pseudo-random number generators (CSPRNGs) that meet established statistical randomness standards is essential for maintaining robust security integrity.