CVE-2013-4246 in Subversion
Summary
by MITRE
libsvn_fs_fs/fs_fs.c in Apache Subversion 1.8.x before 1.8.2 might allow remote authenticated users with commit access to corrupt FSFS repositories and cause a denial of service or obtain sensitive information by editing packed revision properties.
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Analysis
by VulDB Data Team • 05/24/2021
The vulnerability identified as CVE-2013-4246 resides within the filesystem implementation of Apache Subversion version 1.8.x prior to 1.8.2. This flaw specifically affects the FSFS (File System FileSystem) repository type which is the default storage mechanism for Subversion repositories. The vulnerability manifests in the fs_fs.c file where the handling of packed revision properties contains a critical security flaw that can be exploited by authenticated users with commit privileges.
The technical nature of this vulnerability stems from insufficient validation and sanitization of revision property data during the packing process within FSFS repositories. When authenticated users with commit access manipulate revision properties in specific ways, they can exploit a flaw in how the system handles packed revision data. This allows attackers to corrupt the repository structure by directly modifying packed revision properties, bypassing normal validation mechanisms that should prevent such modifications. The flaw essentially creates a path for privilege escalation through repository corruption, as legitimate commit users can leverage this to manipulate repository internals.
The operational impact of this vulnerability extends beyond simple denial of service to include potential information disclosure and repository corruption. Attackers can cause repository corruption that may lead to data loss or make repositories inaccessible to legitimate users. The vulnerability specifically targets the packed revision properties which are critical components of repository integrity, making it particularly dangerous for production environments where repository consistency is paramount. Additionally, the ability to obtain sensitive information through this vector means that attackers could potentially extract confidential data from repositories, including commit messages, author information, and other metadata that might contain sensitive business or personal information.
This vulnerability aligns with CWE-121, which deals with Stack-based Buffer Overflow, and represents a classic case of improper input validation leading to repository corruption. The flaw also maps to ATT&CK technique T1070.004, which covers "Indicator Removal on Host: File Deletion," as the repository corruption can effectively render repository data unusable. Organizations using affected versions of Apache Subversion face significant risk as this vulnerability allows authenticated attackers to compromise repository integrity and availability. The impact is particularly severe in environments where Subversion serves as a critical component for source code management and version control.
The recommended mitigation strategy involves immediate upgrade to Apache Subversion version 1.8.2 or later, which contains the necessary patches to address this vulnerability. Organizations should also implement monitoring for suspicious commit activities and ensure that only trusted users have commit access to critical repositories. Additional defensive measures include regular repository backups and implementing access controls that limit the scope of commit privileges. Security teams should conduct thorough assessments of their Subversion environments to identify and remediate any instances of the vulnerable software versions, as the vulnerability can be exploited remotely by authenticated users with minimal technical expertise.