CVE-2015-0286 in Communications Policy Management
Summary
by MITRE
The ASN1_TYPE_cmp function in crypto/asn1/a_type.c in OpenSSL before 0.9.8zf, 1.0.0 before 1.0.0r, 1.0.1 before 1.0.1m, and 1.0.2 before 1.0.2a does not properly perform boolean-type comparisons, which allows remote attackers to cause a denial of service (invalid read operation and application crash) via a crafted X.509 certificate to an endpoint that uses the certificate-verification feature.
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Analysis
by VulDB Data Team • 09/27/2022
The vulnerability identified as CVE-2015-0286 represents a critical flaw in OpenSSL's handling of ASN.1 type comparisons within the ASN1_TYPE_cmp function located in crypto/asn1/a_type.c. This issue affects multiple OpenSSL versions including 0.9.8 series up to 0.9.8zf, 1.0.0 series up to 1.0.0r, 1.0.1 series up to 1.0.1m, and 1.0.2 series up to 1.0.2a. The flaw stems from improper boolean-type comparisons during X.509 certificate processing, creating a condition where malformed certificate data can trigger unexpected behavior in cryptographic applications that rely on OpenSSL's certificate verification capabilities.
The technical implementation of this vulnerability occurs when the ASN1_TYPE_cmp function fails to correctly handle boolean comparisons between ASN.1 types during certificate validation processes. When a maliciously crafted X.509 certificate is presented to an OpenSSL-based application that performs certificate verification, the function's inadequate boolean comparison logic causes the application to attempt invalid memory reads. This improper handling results in memory access violations that ultimately lead to application crashes and denial of service conditions. The vulnerability specifically impacts the comparison operations within the ASN.1 parsing mechanism, where boolean values are not properly validated before being used in comparison contexts.
From an operational perspective, this vulnerability poses significant risks to systems relying on OpenSSL for secure communications, particularly those handling X.509 certificates in TLS/SSL contexts. Attackers can exploit this weakness by constructing specially formatted certificates that trigger the flawed comparison logic, causing target applications to crash and become unavailable to legitimate users. The impact extends across various protocols and services including web servers, email servers, VPN systems, and any application that validates X.509 certificates through OpenSSL libraries. This vulnerability aligns with CWE-129, which addresses improper handling of boolean comparisons, and represents a classic example of a memory safety issue that can be leveraged for denial of service attacks.
The exploitation of CVE-2015-0286 follows patterns consistent with the ATT&CK framework's privilege escalation and denial of service tactics, where adversaries leverage software vulnerabilities to disrupt service availability. The vulnerability's impact is particularly concerning in environments where certificate verification is a mandatory security control, as attackers can systematically target applications to cause service disruption without requiring authentication or elevated privileges. Organizations using affected OpenSSL versions face potential business disruption and increased risk of service availability attacks, making this vulnerability a priority for immediate remediation.
Mitigation strategies for CVE-2015-0286 primarily focus on upgrading to patched OpenSSL versions, specifically OpenSSL 0.9.8zf, 1.0.0r, 1.0.1m, and 1.0.2a or later releases. System administrators should conduct comprehensive vulnerability assessments to identify all affected applications and services, followed by coordinated patch deployment across the infrastructure. Additional defensive measures include implementing certificate validation policies that limit certificate chain depth, deploying network monitoring to detect unusual certificate processing patterns, and maintaining up-to-date security patches for all OpenSSL-dependent applications. The vulnerability demonstrates the importance of proper input validation and memory safety practices in cryptographic libraries, highlighting the need for rigorous code review processes and automated testing of security-critical functions.