CVE-2020-5791 in Operating System
Summary
by MITRE • 10/21/2020
Improper neutralization of special elements used in an OS command in Nagios XI 5.7.3 allows a remote, authenticated admin user to execute operating system commands with the privileges of the apache user.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2020-5791 represents a critical command injection flaw within Nagios XI version 5.7.3 that stems from inadequate input sanitization in operating system command execution paths. This vulnerability specifically affects the web-based administrative interface of Nagios XI, which is widely deployed for network monitoring and system health tracking across enterprise environments. The flaw exists in how the application processes user-supplied input when constructing operating system commands, creating a pathway for malicious command injection that can be exploited by authenticated administrative users.
The technical implementation of this vulnerability resides in the improper neutralization of special elements within OS command contexts, which directly maps to CWE-77 and CWE-88 within the Common Weakness Enumeration framework. Attackers with administrative privileges can leverage this weakness by crafting malicious input that gets processed into system commands without proper sanitization or escaping mechanisms. The vulnerability manifests when administrative users interact with specific web forms or API endpoints that subsequently execute operating system commands, allowing attackers to inject arbitrary commands that execute with the privileges of the apache user account under which Nagios XI operates. This privilege level typically provides extensive access to system resources, files, and network interfaces, making the impact particularly severe.
The operational impact of this vulnerability extends beyond simple command execution, as it enables attackers to perform a wide range of malicious activities including but not limited to data exfiltration, system reconnaissance, privilege escalation, and persistent backdoor establishment. The fact that the attack requires only administrative authentication means that the vulnerability can be exploited by insiders or compromised administrative accounts, making detection more challenging. The apache user context provides access to web application files, configuration data, and potentially system-level resources that could compromise the entire monitoring infrastructure. This vulnerability directly aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation within the MITRE ATT&CK framework, representing a significant threat to network security monitoring capabilities.
Organizations utilizing Nagios XI 5.7.3 should immediately implement mitigations including applying the vendor-provided security patches, implementing network segmentation to limit administrative access, and conducting comprehensive monitoring for suspicious command execution patterns. Additional defensive measures include implementing principle of least privilege for administrative accounts, enabling multi-factor authentication, and establishing robust audit logging for administrative activities. The vulnerability demonstrates the critical importance of input validation and proper sanitization in web applications, particularly those handling system-level operations, as even authenticated administrative users can pose significant threats when command injection vulnerabilities exist in monitoring and management interfaces.