CVE-2012-1577 in OpenBSD
Summary
by MITRE
lib/libc/stdlib/random.c in OpenBSD returns 0 when seeded with 0.
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Analysis
by VulDB Data Team • 12/11/2019
The vulnerability described in CVE-2012-1577 resides within the random number generation functionality of OpenBSD's standard library implementation. This issue specifically affects the random.c file located in the lib/libc/stdlib directory of the OpenBSD operating system. The flaw manifests when the random number generator is initialized with a seed value of zero, causing the system to return a deterministic value of zero instead of properly seeding the generator with a cryptographically secure random value. This represents a fundamental weakness in the entropy handling mechanism that underpins secure random number generation.
The technical implementation flaw stems from improper handling of the seed parameter within the random number generation algorithm. When developers or applications pass a seed value of zero to the random number generator function, the underlying implementation fails to recognize this as an invalid or insufficient seed and instead treats it as a valid input. This violates the expected behavior of cryptographic random number generators which should produce unpredictable sequences regardless of initial seed values. The vulnerability creates a predictable output pattern that can be exploited by attackers who understand the system's behavior, potentially leading to the compromise of security-sensitive applications that rely on proper random number generation for key generation, session tokens, or cryptographic operations.
The operational impact of this vulnerability extends beyond simple predictability issues and can severely compromise security systems that depend on the quality of random number generation. Applications using the affected OpenBSD library may experience reduced cryptographic strength when seeded with zero, making them vulnerable to attacks that exploit predictable random sequences. This weakness particularly affects systems where random numbers are used for generating encryption keys, session identifiers, or other security-critical values. The vulnerability aligns with CWE-330 Use of Insufficiently Random Values, which specifically addresses the use of pseudo-random number generators that produce predictable outputs. Additionally, this flaw can be leveraged by attackers following techniques described in the ATT&CK framework under T1083 (File and Directory Discovery) and T1059 (Command and Scripting Interpreter) to identify and exploit predictable random number sequences in security-sensitive applications.
Mitigation strategies for this vulnerability require immediate attention from system administrators and developers working with OpenBSD systems. The most effective immediate solution involves updating to a patched version of OpenBSD that properly handles zero seed values by either rejecting them or converting them to appropriate random values through proper entropy collection. Developers should implement additional validation checks in their applications to ensure that seed values are never zero, and should consider using alternative random number generation methods that are not susceptible to this particular flaw. Security monitoring should include detection of applications that may be inadvertently seeding random number generators with zero values, as this could indicate improper implementation or potential exploitation attempts. Organizations should also review their cryptographic implementations to ensure that random number generation is properly seeded with sufficient entropy and that fallback mechanisms exist when primary entropy sources are unavailable or compromised.