CVE-2002-0656 in OpenSSL
Summary
by MITRE
Buffer overflows in OpenSSL 0.9.6d and earlier, and 0.9.7-beta2 and earlier, allow remote attackers to execute arbitrary code via (1) a large client master key in SSL2 or (2) a large session ID in SSL3.
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Analysis
by VulDB Data Team • 03/09/2025
The vulnerability described in CVE-2002-0656 represents a critical buffer overflow flaw affecting OpenSSL implementations version 0.9.6d and earlier, as well as 0.9.7-beta2 and earlier releases. This vulnerability resides within the Secure Sockets Layer protocol implementations that are fundamental to securing internet communications. The flaw manifests in two distinct attack vectors that exploit different components of the SSL protocol stack, creating multiple pathways for remote code execution.
The technical implementation of this vulnerability stems from inadequate input validation within the SSL protocol handling code. In the first vector, attackers can craft malicious client master key values that exceed the allocated buffer space during SSL2 protocol processing. Similarly, the second vector targets SSL3 protocol handling where oversized session IDs can trigger buffer overflows. Both scenarios occur during the handshake process when the SSL implementation attempts to store these oversized values in fixed-size buffers without proper bounds checking. This fundamental flaw in memory management allows attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution.
The operational impact of CVE-2002-0656 is severe and far-reaching across internet infrastructure. Systems running vulnerable OpenSSL versions become susceptible to remote code execution attacks that can compromise entire servers or applications relying on SSL/TLS encryption. The vulnerability affects web servers, email servers, and any network service that utilizes SSL protocol for secure communications. Attackers can exploit these flaws to gain unauthorized access, execute malicious code, and potentially establish persistent backdoors. The remote nature of the attack means that adversaries do not require physical access to target systems, making these vulnerabilities particularly dangerous for organizations with public-facing services.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation. The attack patterns associated with this vulnerability map directly to ATT&CK technique T1071.004, which covers application layer protocol usage, and T1059, covering command and scripting interpreters. Organizations affected by this vulnerability should prioritize immediate patching of all OpenSSL installations, implement network segmentation to limit exposure, and conduct comprehensive vulnerability assessments to identify any systems that may be running older versions. Additionally, monitoring for suspicious network traffic patterns and implementing intrusion detection systems can help identify potential exploitation attempts. The remediation process requires careful testing of patches to ensure compatibility with existing applications while maintaining the security posture of the organization's cryptographic infrastructure.