CVE-2018-1000156 in Patch
Summary
by MITRE
GNU Patch version 2.7.6 contains an input validation vulnerability when processing patch files, specifically the EDITOR_PROGRAM invocation (using ed) can result in code execution. This attack appear to be exploitable via a patch file processed via the patch utility. This is similar to FreeBSD's CVE-2015-1418 however although they share a common ancestry the code bases have diverged over time.
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Analysis
by VulDB Data Team • 04/14/2025
The vulnerability identified as CVE-2018-1000156 affects GNU Patch version 2.7.6 and represents a critical input validation flaw that can lead to arbitrary code execution through malicious patch file processing. This vulnerability specifically targets the EDITOR_PROGRAM invocation mechanism within the patch utility, which utilizes the ed text editor for handling certain patch operations. The flaw arises from insufficient input validation when processing patch files that contain crafted sequences designed to trigger unintended behavior in the underlying ed command execution. The vulnerability demonstrates characteristics consistent with command injection attacks where untrusted input is directly incorporated into system commands without proper sanitization or escaping mechanisms.
The technical implementation of this vulnerability stems from the patch utility's handling of patch files that contain specific patterns intended to manipulate the EDITOR_PROGRAM environment variable or command execution flow. When GNU Patch processes such malicious input, it executes the ed command with potentially dangerous arguments that can be manipulated to execute arbitrary commands on the target system. This vulnerability operates at the intersection of input validation failure and command execution, creating a pathway for attackers to escalate privileges or compromise the system. The flaw is particularly concerning because it leverages legitimate system utilities within the patching process, making detection more challenging and exploitation more stealthy. The vulnerability's classification aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-20, which covers input validation issues that can lead to command injection attacks.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential system compromise, data exfiltration, and privilege escalation scenarios. An attacker who can influence the patch file processing workflow can execute arbitrary commands with the privileges of the user running the patch utility, potentially leading to full system compromise. This vulnerability is particularly dangerous in automated build systems, continuous integration environments, or any scenario where patch files are automatically applied without proper validation. The attack vector requires the victim to process a malicious patch file through the GNU Patch utility, making social engineering or supply chain compromise potential attack methods. The vulnerability's similarity to FreeBSD's CVE-2015-1418 demonstrates how command injection flaws in text processing utilities can persist across different implementations, highlighting the importance of thorough input validation in system utilities. Organizations using GNU Patch for automated patch management or code integration workflows face significant risk from this vulnerability, as it can be exploited through various attack vectors including compromised source code repositories, malicious software updates, or targeted attacks against development environments.
Mitigation strategies for CVE-2018-1000156 should focus on immediate patching of affected GNU Patch installations to version 2.7.7 or later, which contains the necessary fixes for the input validation issues. System administrators should implement strict input validation policies for patch files, particularly in automated environments where patch processing occurs without human intervention. Network segmentation and privilege separation can help limit the potential impact if exploitation occurs, ensuring that patch processing occurs with minimal system privileges. Organizations should also consider implementing automated patch validation procedures that analyze patch content before application, including signature verification and static analysis of patch files. Security monitoring should be enhanced to detect unusual patch processing activities or command execution patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, emphasizing the need for defensive measures that address both the execution and privilege escalation aspects of this vulnerability. Regular security audits of system utilities and patch management processes should be conducted to identify and remediate similar vulnerabilities in other components of the software supply chain.