CVE-2015-7976 in ntp
Summary
by MITRE
The ntpq saveconfig command in NTP 4.1.2, 4.2.x before 4.2.8p6, 4.3, 4.3.25, 4.3.70, and 4.3.77 does not properly filter special characters, which allows attackers to cause unspecified impact via a crafted filename.
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Analysis
by VulDB Data Team • 05/17/2026
The ntpq saveconfig command vulnerability in NTP versions 4.1.2, 4.2.x before 4.2.8p6, 4.3, 4.3.25, 4.3.70, and 4.3.77 represents a critical security flaw that stems from inadequate input validation and sanitization practices. This vulnerability specifically affects the ntpq utility's saveconfig functionality, which is designed to persist network time protocol configuration settings to disk. The flaw exists in how the system processes filename arguments when saving configurations, creating an environment where maliciously crafted filenames can bypass normal security controls and potentially execute arbitrary commands or manipulate system resources. This type of vulnerability falls under the category of command injection or path traversal issues, where insufficient filtering of user-supplied data creates opportunities for unauthorized system access and manipulation.
The technical implementation of this vulnerability exploits the lack of proper character filtering in the saveconfig command's filename processing mechanism. When an attacker provides a specially crafted filename containing special characters such as semicolons, pipes, or other shell metacharacters, the system fails to properly sanitize these inputs before using them in system calls or file operations. This allows attackers to inject additional commands or manipulate the intended file path in ways that were not anticipated by the original system design. The vulnerability is particularly dangerous because it operates at a level where configuration management commands can directly affect system behavior, potentially leading to privilege escalation or complete system compromise. The flaw aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-22, which covers improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability extends beyond simple configuration file manipulation and can result in significant security breaches within network time synchronization environments. Attackers can leverage this weakness to execute arbitrary code on systems running vulnerable NTP versions, potentially gaining unauthorized access to critical network infrastructure. The vulnerability affects systems where ntpq is used for configuration management, particularly in enterprise environments where time synchronization is critical for security logging, authentication systems, and distributed application coordination. The unspecified impact mentioned in the CVE description suggests that the consequences could range from information disclosure to complete system compromise, depending on the execution context and system permissions. This vulnerability directly impacts the integrity and availability of network time services, which are fundamental to maintaining secure and synchronized network operations across distributed systems.
Mitigation strategies for CVE-2015-7976 should prioritize immediate patching of affected NTP versions to 4.2.8p6 or later, as this addresses the root cause of the input filtering deficiency. Organizations should implement network segmentation and access controls to limit who can execute ntpq commands, particularly those with configuration modification capabilities. The principle of least privilege should be enforced by ensuring that only authorized administrators have access to ntpq saveconfig functionality. Additionally, implementing proper input validation at all levels of the application stack, including the command line interface, can prevent similar vulnerabilities from occurring in other components. System monitoring should be enhanced to detect unusual patterns in configuration file modifications or unexpected command executions. This vulnerability demonstrates the importance of adhering to security best practices such as those outlined in the ATT&CK framework, specifically the command and control techniques that involve executing malicious commands through legitimate system tools. Regular security assessments and vulnerability scanning should be conducted to identify similar input validation flaws in other system components, ensuring comprehensive protection against privilege escalation and arbitrary code execution attacks.