CVE-2015-5334 in Mac OS X
Summary
by MITRE
Off-by-one error in the OBJ_obj2txt function in LibreSSL before 2.3.1 allows remote attackers to cause a denial of service (program crash) or possible execute arbitrary code via a crafted X.509 certificate, which triggers a stack-based buffer overflow. Note: this vulnerability exists because of an incorrect fix for CVE-2014-3508.
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Analysis
by VulDB Data Team • 07/11/2022
The CVE-2015-5334 vulnerability represents a critical stack-based buffer overflow in the OBJ_obj2txt function within LibreSSL versions prior to 2.3.1. This flaw arises from an off-by-one error that occurs during the processing of X.509 certificates, specifically when handling object identifiers within certificate structures. The vulnerability demonstrates the complex nature of cryptographic library security where remediation efforts can inadvertently introduce new weaknesses, as this issue stems from an incorrect fix for the previously disclosed CVE-2014-3508. The root cause lies in improper bounds checking during the conversion of object identifiers to text format, where the function fails to account for the null terminator required in string operations, creating a condition where one additional byte can be written beyond the allocated buffer space.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution, making it particularly dangerous in network-facing applications that process untrusted X.509 certificates. Attackers can craft malicious certificates that, when processed by vulnerable LibreSSL implementations, trigger the buffer overflow condition. This allows adversaries to manipulate the stack memory layout, potentially leading to arbitrary code execution with the privileges of the affected process. The vulnerability affects any application relying on LibreSSL for SSL/TLS operations, including web servers, email servers, and other network services that validate X.509 certificates. The stack-based nature of the overflow means that the attack can be reliably executed across different platforms and architectures, as the memory layout patterns remain consistent in typical operating system environments.
From a cybersecurity perspective, this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions. The ATT&CK framework categorizes this as a code injection technique under the T1055 category, where adversaries leverage memory corruption vulnerabilities to execute malicious code. The vulnerability's exploitation requires minimal privileges since the attack targets the cryptographic library itself rather than requiring specific application-level access. Organizations using affected LibreSSL versions face significant risk as the flaw can be exploited through standard network protocols such as HTTPS, SMTPS, and LDAPS without requiring user interaction or specific authentication. The vulnerability's presence in the certificate processing pipeline makes it particularly insidious as it can be triggered during routine certificate validation operations, potentially allowing attackers to maintain persistent access through certificate manipulation attacks. Mitigation efforts must focus on immediate version upgrades to LibreSSL 2.3.1 or later, while also implementing certificate validation controls and monitoring for suspicious certificate processing activities that may indicate exploitation attempts.