CVE-2015-5259 in Subversion
Summary
by MITRE
Integer overflow in the read_string function in libsvn_ra_svn/marshal.c in Apache Subversion 1.9.x before 1.9.3 allows remote attackers to execute arbitrary code via an svn:// protocol string, which triggers a heap-based buffer overflow and an out-of-bounds read.
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Analysis
by VulDB Data Team • 07/02/2022
The vulnerability CVE-2015-5259 represents a critical integer overflow flaw within Apache Subversion's svn protocol handling mechanism. This issue exists in the read_string function located in libsvn_ra_svn/marshal.c, specifically affecting Apache Subversion versions 1.9.x prior to 1.9.3. The vulnerability manifests when processing svn:// protocol strings, creating a dangerous condition that can be exploited by remote attackers to execute arbitrary code on vulnerable systems. The flaw stems from inadequate input validation and overflow protection within the string parsing logic, allowing maliciously crafted protocol data to cause memory corruption.
The technical implementation of this vulnerability involves a heap-based buffer overflow combined with an out-of-bounds read operation. When the read_string function processes an svn:// protocol string, it fails to properly validate the length parameter of the incoming string data. This inadequate validation allows an attacker to craft a specially formatted string that causes integer overflow during size calculations, resulting in insufficient buffer allocation. The subsequent heap overflow creates memory corruption that can be leveraged to overwrite critical program memory locations, while the out-of-bounds read operation provides additional attack surface for code execution.
From an operational impact perspective, this vulnerability poses significant risk to organizations utilizing Apache Subversion for version control operations. Remote attackers can exploit this flaw without authentication, making it particularly dangerous in environments where svn:// protocol endpoints are exposed to untrusted networks. The successful exploitation can lead to complete system compromise, allowing attackers to execute arbitrary commands with the privileges of the Subversion service account. This vulnerability affects not only the local system but can also potentially enable further lateral movement within network environments where Subversion servers serve as access points.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1203, involving exploitation of remote services through protocol manipulation. Organizations should implement immediate mitigations including upgrading to Apache Subversion 1.9.3 or later versions, which contain the necessary patches to prevent integer overflow conditions in the read_string function. Network segmentation and firewall rules should be implemented to restrict access to svn:// protocol endpoints, while monitoring systems should be configured to detect anomalous protocol string patterns that might indicate exploitation attempts. Additionally, regular security assessments of version control infrastructure and implementation of automated patch management processes are essential for maintaining defensive posture against similar vulnerabilities in the future.