CVE-2020-5792 in Nagios XI
Summary
by MITRE • 10/21/2020
Improper neutralization of argument delimiters in a command in Nagios XI 5.7.3 allows a remote, authenticated admin user to write to arbitrary files and ultimately execute code with the privileges of the apache user.
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Analysis
by VulDB Data Team • 11/22/2020
The vulnerability identified as CVE-2020-5792 represents a critical command injection flaw within Nagios XI version 5.7.3 that exploits improper handling of argument delimiters in command execution contexts. This weakness specifically affects authenticated administrative users who can leverage the vulnerability to escalate their privileges and execute arbitrary code on the target system. The vulnerability resides in the way the application processes user-supplied input when constructing system commands, creating a pathway for malicious command injection that bypasses normal security controls.
From a technical perspective, the flaw manifests as insufficient sanitization of command arguments that are passed to system execution functions. When administrative users submit certain commands through the web interface, the application fails to properly escape or quote argument delimiters, allowing attackers to inject additional commands that are subsequently executed by the underlying operating system. This type of vulnerability aligns with CWE-77 and CWE-88 categories, which specifically address improper neutralization of special elements used in command execution and command injection attacks respectively. The vulnerability operates at the intersection of input validation and command construction, making it particularly dangerous in environments where administrative privileges are required to exploit the flaw.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the ability to write to arbitrary files on the system and ultimately achieve complete control over the affected Nagios XI instance. Since the application runs with apache user privileges, successful exploitation results in the attacker gaining control over the web server process, which typically has access to monitoring data, configuration files, and potentially other system resources. This privilege escalation capability means that even if the initial attack vector requires administrative credentials, the final outcome provides a persistent backdoor that can be used for further lateral movement within the network infrastructure. The attack surface is particularly concerning given that Nagios XI is commonly deployed in critical infrastructure monitoring environments where such access could lead to significant operational disruption.
Security professionals should implement multiple layers of mitigation to address this vulnerability effectively. Immediate remediation involves upgrading to a patched version of Nagios XI that properly handles command argument delimiters and implements proper input sanitization. Organizations should also consider implementing network segmentation to limit access to Nagios XI systems and restrict administrative access to only necessary personnel. Additionally, monitoring for unusual file creation patterns and command execution activities can help detect exploitation attempts. The vulnerability demonstrates the importance of following secure coding practices and implementing proper input validation as outlined in the OWASP Top Ten and MITRE ATT&CK framework's command and control tactics, where such flaws represent common attack vectors for privilege escalation and persistent access. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other applications within the network infrastructure that may be susceptible to similar command injection attacks.