CVE-2012-1558 in CyaSSL
Summary
by MITRE
yaSSL CyaSSL before 2.0.8 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted X.509 certificate.
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Analysis
by VulDB Data Team • 02/15/2019
The vulnerability identified as CVE-2012-1558 affects the yaSSL CyaSSL library version 2.0.7 and earlier, representing a critical denial of service flaw that can be exploited remotely by attackers. This vulnerability stems from improper handling of malformed X.509 certificates within the cryptographic library implementation, specifically manifesting as a NULL pointer dereference during certificate validation processes. The issue occurs when the library encounters a specially crafted X.509 certificate that contains malformed or unexpected data structures, leading to application crashes and system unavailability.
The technical root cause of this vulnerability aligns with CWE-476, which describes NULL pointer dereference conditions in software implementations. When the yaSSL CyaSSL library processes an attacker-controlled X.509 certificate, the certificate parsing logic fails to properly validate certificate fields or handle edge cases in certificate structure interpretation. This failure results in the library attempting to dereference a NULL pointer during certificate validation, causing an application crash that can be leveraged for denial of service attacks. The vulnerability operates at the cryptographic library level, affecting any application that relies on yaSSL CyaSSL for secure communications and certificate validation.
From an operational impact perspective, this vulnerability poses significant risks to systems that depend on yaSSL CyaSSL for secure socket layer communications, including web servers, email servers, and other network services. Attackers can exploit this vulnerability by presenting a malformed X.509 certificate to vulnerable applications, causing them to crash and potentially leading to extended service outages. The remote nature of the attack means that adversaries do not require local access or authentication to exploit the vulnerability, making it particularly dangerous in networked environments where certificate validation is routinely performed. This vulnerability directly impacts the availability aspect of the CIA triad, potentially rendering systems inaccessible to legitimate users.
The exploitation of CVE-2012-1558 aligns with techniques described in the MITRE ATT&CK framework under the T1499.004 sub-technique for Network Denial of Service, where adversaries leverage software vulnerabilities to disrupt service availability. The attack vector typically involves sending malicious X.509 certificates to vulnerable applications, which then crash upon attempting to process the malformed certificate data. Organizations using affected versions of yaSSL CyaSSL should prioritize immediate patching to address this vulnerability. The recommended mitigation involves upgrading to version 2.0.8 or later, where the certificate parsing logic has been corrected to properly handle malformed inputs and prevent NULL pointer dereference conditions. Additionally, network administrators should consider implementing certificate validation policies and monitoring for unusual certificate-related traffic patterns that might indicate exploitation attempts.