CVE-2012-2131 in OpenSSL
Summary
by MITRE
Multiple integer signedness errors in crypto/buffer/buffer.c in OpenSSL 0.9.8v allow remote attackers to conduct buffer overflow attacks, and cause a denial of service (memory corruption) or possibly have unspecified other impact, via crafted DER data, as demonstrated by an X.509 certificate or an RSA public key. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-2110.
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Analysis
by VulDB Data Team • 11/18/2024
The vulnerability identified as CVE-2012-2131 represents a critical security flaw in OpenSSL 0.9.8v that stems from integer signedness errors within the crypto/buffer/buffer.c file. This issue specifically affects the handling of DER encoded data structures used in X.509 certificates and RSA public keys, creating a pathway for remote attackers to exploit buffer overflow conditions. The vulnerability emerged as an incomplete remediation for CVE-2012-2110, indicating that previous attempts to address similar issues were insufficiently comprehensive. These signedness errors occur when the software fails to properly validate the sign of integer values during buffer size calculations, leading to miscalculations that can result in memory corruption. The flaw manifests when processing crafted DER data that contains maliciously constructed integer values, which can cause the application to allocate insufficient buffer space or incorrectly calculate buffer boundaries.
The technical implementation of this vulnerability involves the manipulation of integer values that control buffer allocation and memory handling within OpenSSL's cryptographic processing routines. When OpenSSL encounters DER encoded data containing crafted signed integers, the system's failure to properly handle unsigned integer arithmetic results in buffer overflows that can corrupt adjacent memory regions. This occurs because the software assumes certain integer values will be positive and uses them directly in buffer size calculations without proper validation of their sign. The impact extends beyond simple memory corruption to potentially enable arbitrary code execution or complete denial of service conditions, depending on the specific exploitation scenario. The vulnerability affects the fundamental cryptographic operations that underpin secure communications, making it particularly dangerous in environments where OpenSSL is used for SSL/TLS implementations and certificate validation.
The operational implications of CVE-2012-2131 are severe and far-reaching across numerous security systems that depend on OpenSSL for cryptographic operations. Any system processing X.509 certificates or RSA public keys through OpenSSL 0.9.8v becomes vulnerable to remote exploitation, potentially affecting web servers, email servers, VPN systems, and any application that relies on secure certificate validation. The vulnerability's potential for unspecified other impacts means that attackers could leverage it for various malicious activities including privilege escalation, data exfiltration, or disruption of critical services. The fact that this vulnerability exists due to an incomplete fix for CVE-2012-2110 demonstrates the complexity of cryptographic security issues and the difficulty of ensuring comprehensive patching of integer arithmetic flaws. Organizations using affected OpenSSL versions face significant risk of compromise, particularly in environments where certificate validation occurs without proper input sanitization.
Mitigation strategies for CVE-2012-2131 require immediate action to upgrade to patched versions of OpenSSL, specifically versions 0.9.8w or later, which contain proper fixes for the signedness errors. System administrators should prioritize updating all affected OpenSSL installations and verify that the patch correctly addresses the integer arithmetic validation issues. Additionally, implementing network monitoring to detect attempts to process malformed DER data can help identify potential exploitation attempts. The vulnerability aligns with CWE-190, which covers integer overflow and signedness errors, and represents a typical example of how incomplete fixes can leave systems vulnerable to continued exploitation. Organizations should also consider implementing certificate validation policies that limit the processing of untrusted certificates and ensure that all cryptographic libraries are kept current with security patches. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service techniques, as it can enable attackers to compromise system integrity and availability through careful manipulation of cryptographic data structures.