CVE-2012-0027 in OpenSSL
Summary
by MITRE
The GOST ENGINE in OpenSSL before 1.0.0f does not properly handle invalid parameters for the GOST block cipher, which allows remote attackers to cause a denial of service (daemon crash) via crafted data from a TLS client.
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Analysis
by VulDB Data Team • 03/20/2021
The vulnerability identified as CVE-2012-0027 resides within the GOST ENGINE implementation of OpenSSL versions prior to 1.0.0f, representing a critical flaw in cryptographic processing that can lead to daemon crashes and service disruption. This vulnerability specifically affects the GOST block cipher algorithm, which is a Russian standard for symmetric encryption that OpenSSL supports through its engine framework. The GOST cipher implementation within OpenSSL's cryptographic library is designed to handle various parameter sets and key lengths according to the Federal Standard of the Russian Federation. However, the flaw manifests when the engine encounters malformed or invalid parameter structures during TLS handshakes, creating a scenario where the daemon process becomes unstable and terminates unexpectedly.
The technical root cause of this vulnerability stems from inadequate input validation within the GOST ENGINE's parameter handling routines. When a TLS client establishes a connection and sends crafted parameter data that does not conform to expected GOST cipher specifications, the engine fails to properly validate these inputs before processing them. This lack of proper validation leads to memory corruption or undefined behavior within the cryptographic engine, ultimately causing the OpenSSL daemon to crash. The vulnerability operates at the protocol level during TLS negotiation, specifically when the GOST cipher suite is negotiated between client and server. Attackers can exploit this by constructing malicious TLS handshake messages that contain invalid GOST parameters, triggering the engine's failure state without requiring authentication or privileged access.
From an operational perspective, this vulnerability presents a significant denial of service threat to systems running vulnerable OpenSSL versions, particularly those that support GOST cipher suites in their TLS configurations. The impact extends beyond simple service disruption, as it can affect availability of critical infrastructure components that rely on OpenSSL for secure communications. Systems that implement GOST cipher support, such as certain government, military, or financial institutions using Russian cryptographic standards, face particular risk. The vulnerability affects both server and client implementations within OpenSSL, meaning that either endpoint in a TLS connection could be targeted. Network administrators and security teams must consider that this flaw can be exploited remotely without requiring user interaction or credentials, making it particularly dangerous in environments where OpenSSL serves as a core security component.
Mitigation strategies for CVE-2012-0027 primarily focus on upgrading to OpenSSL version 1.0.0f or later, where the GOST ENGINE has been patched to properly validate parameter inputs. Organizations should also consider disabling GOST cipher suites in their OpenSSL configurations if they are not actively using them, thereby eliminating the attack surface entirely. Security monitoring should include detection of unusual TLS handshake patterns and daemon crashes that might indicate exploitation attempts. Network segmentation and intrusion detection systems can help identify and block malicious TLS handshake attempts targeting this vulnerability. The weakness aligns with CWE-248, which addresses "Uncaught Exception," and maps to ATT&CK technique T1499.004 for "Endpoint Denial of Service," as it enables attackers to disrupt service availability through crafted cryptographic parameters. Organizations should also implement regular vulnerability assessments and maintain updated OpenSSL installations to prevent similar issues from arising in future deployments.