CVE-2001-1141 in OpenSSL
Summary
by MITRE
The Pseudo-Random Number Generator (PRNG) in SSLeay and OpenSSL before 0.9.6b allows attackers to use the output of small PRNG requests to determine the internal state information, which could be used by attackers to predict future pseudo-random numbers.
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Analysis
by VulDB Data Team • 05/09/2019
The vulnerability described in CVE-2001-1141 represents a critical weakness in the cryptographic implementation of SSLeay and OpenSSL versions prior to 0.9.6b. This issue specifically targets the pseudo-random number generator component that forms the foundation of secure cryptographic operations within these widely-used security libraries. The flaw enables attackers to exploit the predictable nature of the PRNG output, fundamentally compromising the security assurances that cryptographic systems rely upon for protecting sensitive data and communications.
The technical flaw manifests through a design weakness in how the PRNG handles small output requests, allowing attackers to observe sufficient information from these limited outputs to reconstruct the internal state of the generator. This occurs because the implementation does not properly maintain the entropy and randomness properties that cryptographic PRNGs require to prevent state recovery attacks. The vulnerability specifically relates to the mathematical properties of the underlying algorithm used for generating pseudo-random numbers, where the internal state becomes computationally recoverable through analysis of the output sequences. This weakness falls under the category of improper random number generation as classified by CWE-330, which addresses insufficient entropy in cryptographic implementations.
The operational impact of this vulnerability is severe and far-reaching, as it directly undermines the security of any system relying on these cryptographic libraries for SSL/TLS connections, digital signatures, or key generation. Attackers who can predict future pseudo-random numbers gain the ability to compromise session keys, forge digital signatures, and potentially decrypt sensitive communications. The attack vector typically involves monitoring network traffic to capture small amounts of PRNG output, then using mathematical techniques to reverse-engineer the internal state. This vulnerability has been classified under the MITRE ATT&CK framework as part of the credential access and defense evasion techniques, specifically targeting the weakness in cryptographic implementations that enables adversaries to bypass security controls.
Mitigation strategies for this vulnerability require immediate patching of affected systems to upgrade to OpenSSL 0.9.6b or later versions where the PRNG implementation has been corrected. Organizations should conduct comprehensive inventory checks to identify all systems using vulnerable versions of SSLeay or OpenSSL, particularly those handling sensitive data or providing secure communications. Security teams should implement monitoring for unusual patterns in cryptographic operations that might indicate exploitation attempts, while also ensuring that all cryptographic keys and certificates generated before patching are considered compromised and rotated. The fix typically involves strengthening the PRNG initialization process and ensuring proper state management to prevent information leakage that could lead to state recovery attacks. System administrators should also consider implementing additional cryptographic security measures such as hardware security modules or trusted platform modules to provide more robust random number generation capabilities.