CVE-2020-24899 in Nagios XI
Summary
by MITRE • 02/16/2021
Nagios XI 5.7.2 is affected by a remote code execution (RCE) vulnerability. An authenticated user can inject additional commands into normal webapp query.
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Analysis
by VulDB Data Team • 03/01/2021
The vulnerability identified as CVE-2020-24899 represents a critical remote code execution flaw in Nagios XI version 5.7.2 that fundamentally compromises the security posture of affected systems. This issue stems from insufficient input validation within the web application's query processing mechanisms, allowing authenticated attackers to inject malicious commands that are subsequently executed on the target server. The vulnerability exists within the application's handling of user-supplied data in web requests, creating a pathway for attackers to escalate their privileges and gain full control over the affected Nagios XI instance. The flaw is particularly dangerous because it requires only authentication credentials, making it accessible to both internal and external threat actors who have gained access to legitimate user accounts.
The technical implementation of this vulnerability resides in the web application's parameter handling and command execution processes, which do not properly sanitize or validate user input before incorporating it into system commands. This type of vulnerability is classified as CWE-77 in the Common Weakness Enumeration catalog, specifically representing "Improper Neutralization of Special Elements used in a Command ('Command Injection')." The flaw manifests when authenticated users submit crafted queries that contain malicious command sequences, which are then executed without proper sanitization or context-aware escaping. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the web application user, typically running with elevated system permissions. The attack vector operates through standard web application interfaces, making it difficult to detect and trace through conventional network monitoring tools.
The operational impact of CVE-2020-24899 extends far beyond simple unauthorized access, as it provides attackers with complete system compromise capabilities that align with the tactics described in the MITRE ATT&CK framework under the Tactic of Execution and Privilege Escalation. Once exploited, attackers can establish persistent backdoors, exfiltrate sensitive monitoring data, modify system configurations, and potentially use the compromised Nagios XI instance as a launchpad for lateral movement within the network infrastructure. The vulnerability affects the core monitoring functionality of Nagios XI, which typically operates with high-privilege accounts, creating a significant risk for organizations that rely on this system for critical infrastructure monitoring. The impact is particularly severe in environments where Nagios XI serves as a central monitoring point for network security tools, as it provides attackers with access to critical system information and monitoring capabilities.
Mitigation strategies for CVE-2020-24899 should prioritize immediate patching of the affected Nagios XI version to the latest available release that addresses this specific vulnerability. Organizations must also implement network segmentation and access controls to limit the scope of potential exploitation, ensuring that only authorized personnel can access the Nagios XI web interface. Additional defensive measures include implementing web application firewalls to detect and block suspicious command injection patterns, enforcing strict input validation at all application entry points, and conducting regular security assessments of monitoring systems. Security teams should also establish monitoring for unusual command execution patterns and implement proper access logging to detect unauthorized use of the vulnerable functionality. The vulnerability demonstrates the critical importance of maintaining up-to-date software versions and proper input validation practices in web applications, as these measures serve as fundamental defenses against command injection attacks that can lead to complete system compromise.