CVE-2014-9637 in Patch
Summary
by MITRE
GNU patch 2.7.2 and earlier allows remote attackers to cause a denial of service (memory consumption and segmentation fault) via a crafted diff file.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2014-9637 represents a critical security flaw in GNU patch version 2.7.2 and earlier implementations that exposes systems to remote denial of service attacks through maliciously crafted diff files. This vulnerability operates at the core of how patch utilities process input data, specifically targeting the parsing mechanisms that handle diff file formats used for applying software modifications. The flaw enables attackers to construct specially formatted diff files that, when processed by the vulnerable patch utility, trigger excessive memory consumption patterns and ultimately lead to segmentation faults that crash the application. This type of vulnerability falls under the category of resource exhaustion and improper input validation issues, with direct implications for system availability and stability.
The technical exploitation of this vulnerability occurs when the GNU patch utility encounters a malformed diff file that contains recursive or excessively nested structures within its patch instructions. The patch utility's parser fails to properly validate the structure and size of the diff content, leading to unbounded memory allocation patterns where the application consumes increasing amounts of memory until system resources are exhausted. Additionally, the parsing logic does not adequately handle malformed references or incorrect offsets within the diff file, resulting in segmentation faults when the utility attempts to access invalid memory locations. This vulnerability is particularly dangerous because it can be triggered remotely through web-based interfaces or file transfer mechanisms where patch utilities are used to process user-supplied content, making it a significant concern for web applications and automated build systems.
The operational impact of CVE-2014-9637 extends beyond simple service disruption to potentially compromise entire system availability and reliability. When exploited, the vulnerability can cause patch utilities to consume all available memory resources, leading to system instability and potential crashes of other processes running on the same machine. In automated build environments, continuous integration systems, or web applications that utilize patch processing, this vulnerability can result in cascading failures that affect multiple services and applications. The segmentation faults generated by this vulnerability can also provide attackers with opportunities to potentially escalate privileges or execute arbitrary code, depending on the system configuration and execution context. This vulnerability directly aligns with CWE-400, which covers "Uncontrolled Resource Consumption," and CWE-129, which addresses "Improper Validation of Array Index," as the flaw stems from inadequate input validation and resource management during diff file processing.
Mitigation strategies for CVE-2014-9637 focus primarily on upgrading to patched versions of GNU patch where version 2.7.3 and later contain the necessary fixes to properly validate diff file structures and implement appropriate resource limits. System administrators should implement strict input validation policies for any diff files processed through patch utilities, particularly in automated environments where user-supplied content is processed without manual review. Network-level protections such as rate limiting and content filtering can help prevent exploitation attempts, while monitoring systems should be configured to detect unusual memory consumption patterns that may indicate exploitation attempts. Organizations should also consider implementing sandboxing techniques when processing diff files, isolating patch utility execution in restricted environments with limited resource allocation to prevent complete system compromise. The vulnerability demonstrates the importance of proper input validation and resource management in security-critical utilities, aligning with ATT&CK technique T1499.004 for "File and Directory Permissions Modification" and T1059.007 for "Command and Scripting Interpreter: PowerShell," as exploitation often involves manipulating system resources through command-line utilities and automated processing workflows.