CVE-2013-1849 in Subversion
Summary
by MITRE
The mod_dav_svn Apache HTTPD server module in Subversion 1.6.x through 1.6.20 and 1.7.0 through 1.7.8 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a PROPFIND request for an activity URL.
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Analysis
by VulDB Data Team • 01/02/2022
The vulnerability identified as CVE-2013-1849 affects the mod_dav_svn Apache HTTPD server module which is part of the Subversion version control system. This issue exists in multiple versions including 1.6.x through 1.6.20 and 1.7.0 through 1.7.8, representing a significant security concern for organizations relying on Apache HTTPD servers with Subversion support. The flaw manifests as a denial of service condition that can be triggered remotely, making it particularly dangerous for web-facing servers that provide version control services through the Apache web server interface.
The technical root cause of this vulnerability lies in improper input validation within the mod_dav_svn module when processing PROPFIND requests targeting activity URLs. When a malicious actor sends a specially crafted PROPFIND request that references an activity URL, the module fails to properly handle the request parameters, resulting in a NULL pointer dereference. This programming error occurs because the code does not adequately validate or sanitize the URL structure before attempting to access memory locations that may not have been properly initialized. The NULL pointer dereference causes the Apache HTTPD process to crash and terminate, effectively rendering the version control service unavailable to legitimate users.
The operational impact of CVE-2013-1849 extends beyond simple service disruption as it represents a potential vector for broader system compromise. When the Apache process crashes due to this vulnerability, it can lead to complete denial of service for all Subversion services hosted on that server, affecting multiple users and potentially disrupting development workflows. The vulnerability is particularly concerning because it requires minimal effort from attackers to exploit, as the malicious request can be crafted using standard HTTP tools and does not require authentication or elevated privileges. This makes it an attractive target for automated attacks or opportunistic exploitation.
Organizations affected by this vulnerability should prioritize immediate remediation through patching or upgrading their Subversion installations to versions that contain the necessary fixes. The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a classic example of how improper error handling can lead to denial of service attacks. From an ATT&CK framework perspective, this vulnerability could be categorized under initial access and privilege escalation techniques, as attackers might use it to disrupt services before attempting more sophisticated attacks against the underlying system. Mitigation strategies should include implementing network-level protections such as firewalls to restrict access to Subversion endpoints, monitoring for unusual PROPFIND request patterns, and maintaining up-to-date security patches across all affected systems. Additionally, administrators should consider implementing intrusion detection systems that can identify and alert on suspicious HTTP request patterns that may indicate exploitation attempts.