CVE-2015-5343 in Subversion
Summary
by MITRE
Integer overflow in util.c in mod_dav_svn in Apache Subversion 1.7.x, 1.8.x before 1.8.15, and 1.9.x before 1.9.3 allows remote authenticated users to cause a denial of service (subversion server crash or memory consumption) and possibly execute arbitrary code via a skel-encoded request body, which triggers an out-of-bounds read and heap-based buffer overflow.
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Analysis
by VulDB Data Team • 07/24/2022
The vulnerability identified as CVE-2015-5343 represents a critical integer overflow flaw within the Apache Subversion mod_dav_svn module that affects versions 1.7.x through 1.8.14 and 1.9.x through 1.9.2. This vulnerability resides in the util.c file and specifically targets the handling of skel-encoded request bodies during webDAV operations. The flaw manifests when the server processes malformed request data that contains oversized integer values, leading to unpredictable behavior in memory management operations. According to CWE-190, this vulnerability falls under integer overflow conditions where an integer value exceeds the maximum representable value for its data type, creating a cascade of memory corruption issues.
The technical exploitation of this vulnerability occurs through crafted skel-encoded request bodies that contain maliciously constructed integer values. When the mod_dav_svn module processes these requests, the integer overflow triggers an out-of-bounds read operation followed by a heap-based buffer overflow. This sequence of events creates a condition where the server's memory management becomes corrupted, potentially leading to complete server crashes or excessive memory consumption that can be leveraged for denial of service attacks. The vulnerability's impact extends beyond simple service disruption as the heap-based buffer overflow creates opportunities for arbitrary code execution, making this a severe security concern for any organization relying on Subversion server infrastructure.
From an operational perspective, this vulnerability presents significant risks to organizations using Apache Subversion servers in production environments, particularly those with webDAV access enabled. The authenticated nature of the attack means that adversaries must first obtain valid credentials to exploit the vulnerability, but this does not mitigate the risk as compromised accounts can be used to launch attacks. The potential for remote code execution makes this vulnerability particularly dangerous as it could allow attackers to gain full control over the affected server, potentially leading to data breaches, privilege escalation, and further lateral movement within the network. The vulnerability affects a wide range of Subversion server deployments, including those used for version control of source code, configuration files, and other critical business assets.
Mitigation strategies for CVE-2015-5343 should prioritize immediate patching of affected Subversion installations to versions 1.8.15 or 1.9.3 and later. Organizations should implement network-level controls to restrict access to Subversion servers and monitor for suspicious request patterns that may indicate exploitation attempts. Security teams should also consider implementing intrusion detection systems that can identify malformed skel-encoded requests and establish robust access control policies to limit the number of authenticated users with webDAV privileges. According to ATT&CK framework, this vulnerability could be leveraged as part of a broader attack chain under techniques such as privilege escalation and persistence, making comprehensive monitoring and response procedures essential. Regular security assessments of Subversion server configurations and access controls should be conducted to ensure continued protection against this and similar vulnerabilities.