CVE-2015-1196 in patch
Summary
by MITRE
GNU patch 2.7.1 allows remote attackers to write to arbitrary files via a symlink attack in a patch file.
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Analysis
by VulDB Data Team • 04/11/2022
The vulnerability identified as CVE-2015-1196 represents a critical security flaw in GNU patch version 2.7.1 that enables remote attackers to perform unauthorized file operations through malicious symlink manipulation. This issue arises from the patch utility's improper handling of symbolic links during the patch application process, creating a path traversal condition that can be exploited by adversaries to write data to unintended locations on the target system. The vulnerability specifically manifests when patch files contain carefully crafted symbolic link references that point to sensitive system files or directories outside the intended target scope.
The technical root cause of this vulnerability stems from insufficient validation of file paths and symbolic link resolution within the GNU patch utility's file handling mechanisms. When patch processes a malicious patch file containing symbolic links, it fails to properly verify whether the target of the symlink points to an authorized location, allowing the patch operation to proceed and write content to arbitrary file paths. This behavior violates fundamental security principles of file access control and path validation, creating an attack surface where remote adversaries can manipulate file system contents without proper authorization. The flaw is classified under CWE-59 as improper link resolution, specifically demonstrating a path traversal vulnerability that permits unauthorized file system access.
The operational impact of CVE-2015-1196 extends beyond simple file corruption or modification, as it enables attackers to potentially overwrite critical system files, install malicious payloads, or create backdoor access points within the target environment. Attackers can leverage this vulnerability to escalate privileges, modify system configurations, or establish persistent access by writing to system binaries, configuration files, or user account databases. The remote nature of the attack means that adversaries can exploit this vulnerability without requiring physical access to the system, making it particularly dangerous in networked environments where patch files might be downloaded from untrusted sources. This vulnerability directly aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1078.004 for valid accounts, as it can be used to gain unauthorized access and execute malicious code through compromised patch operations.
Mitigation strategies for CVE-2015-1196 require immediate patching of affected GNU patch installations to versions that properly validate symbolic link targets and implement proper path resolution checks. Organizations should also implement strict file access controls and sandboxing mechanisms around patch application processes, ensuring that patch utilities operate with minimal privileges and cannot write to critical system locations. Network administrators should establish content filtering measures to prevent execution of patch files from untrusted sources and implement automated scanning of patch files for malicious symlink patterns. Additionally, system hardening practices should include disabling automatic patch application from external sources and implementing comprehensive monitoring of file system modifications to detect unauthorized writes that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and path resolution in security-critical utilities, emphasizing the need for robust security testing of system administration tools.