CVE-2011-1752 in Subversion
Summary
by MITRE
The mod_dav_svn module for the Apache HTTP Server, as distributed in Apache Subversion before 1.6.17, allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a request for a baselined WebDAV resource, as exploited in the wild in May 2011.
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Analysis
by VulDB Data Team • 12/08/2024
The vulnerability identified as CVE-2011-1752 represents a critical denial of service weakness within the mod_dav_svn module of the Apache HTTP Server ecosystem. This module serves as the WebDAV interface for Apache Subversion repositories, enabling remote clients to interact with version control systems through HTTP protocols. The flaw manifests when the module processes requests targeting baselined WebDAV resources, which are fundamental components in distributed version control operations. The vulnerability was actively exploited in the wild during May 2011, demonstrating its real-world impact and the urgency of addressing such security gaps in enterprise environments that rely heavily on version control infrastructure.
The technical root cause of this vulnerability stems from a NULL pointer dereference condition within the mod_dav_svn module's handling of specific WebDAV requests. When processing a request for a baselined resource, the module fails to properly validate or initialize certain pointer variables before attempting to dereference them. This programming error leads to a crash of the Apache daemon process, effectively rendering the web server unavailable to legitimate users. The flaw specifically occurs in the module's resource management logic where it attempts to access memory locations that have not been properly allocated or initialized, resulting in an immediate system termination. This type of vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is classified as a common weakness in software development practices.
The operational impact of CVE-2011-1752 extends beyond simple service disruption, as it affects organizations that depend on Apache Subversion for their software development workflows. When exploited, the vulnerability can cause complete unavailability of version control repositories, halting development activities and potentially leading to significant business disruption. The daemon crash affects not only the specific repository being targeted but can also impact the entire Apache server instance, potentially affecting other hosted applications and services running on the same server. From an attacker perspective, this vulnerability requires minimal technical expertise to exploit, making it particularly dangerous as it can be leveraged by adversaries to create service interruptions without requiring sophisticated attack capabilities. The vulnerability's exploitation aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries target network infrastructure to disrupt service availability.
Organizations affected by this vulnerability should prioritize immediate remediation through patching the Apache Subversion installation to version 1.6.17 or later, which contains the necessary code modifications to prevent the NULL pointer dereference condition. System administrators should also implement monitoring solutions to detect unusual patterns of WebDAV requests that might indicate exploitation attempts, as well as establish robust incident response procedures to address potential service disruptions. The vulnerability highlights the importance of regular security updates and the necessity of maintaining current versions of critical server components. Additionally, organizations should consider implementing network segmentation and access controls to limit exposure of WebDAV-enabled servers to untrusted networks, reducing the attack surface for such vulnerabilities. The incident serves as a reminder of the critical need for thorough code review processes and proper input validation in server-side applications to prevent similar memory corruption vulnerabilities from occurring in the future.