CVE-2018-8735 in Nagios XI
Summary
by MITRE
Remote command execution (RCE) vulnerability in Nagios XI 5.2.x through 5.4.x before 5.4.13 allows an attacker to execute arbitrary commands on the target system, aka OS command injection.
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Analysis
by VulDB Data Team • 12/20/2024
The vulnerability identified as CVE-2018-8735 represents a critical remote command execution flaw in Nagios XI versions 5.2.x through 5.4.x prior to 5.4.13. This issue manifests as an operating system command injection vulnerability that enables attackers to execute arbitrary commands on the targeted system with the privileges of the Nagios service account. The flaw exists within the web interface of Nagios XI, specifically in how the application processes user-supplied input when handling certain API endpoints and configuration parameters. The vulnerability stems from insufficient input validation and improper sanitization of user-provided data before incorporating it into system commands, creating a direct pathway for malicious code execution.
The technical exploitation of this vulnerability occurs when an attacker submits malicious input through web forms or API calls that are subsequently processed by the Nagios XI application. The vulnerable code fails to properly escape or filter special characters that could alter the intended command execution flow, allowing attackers to inject additional commands that execute on the underlying operating system. This type of vulnerability maps directly to CWE-77 and CWE-88 within the Common Weakness Enumeration framework, specifically addressing improper neutralization of special elements used in command injection attacks. The attack vector requires minimal privileges since the application typically runs with elevated permissions to perform monitoring tasks, potentially granting attackers full system access or at minimum the ability to compromise the monitoring infrastructure.
The operational impact of CVE-2018-8735 extends beyond simple command execution, as it can lead to complete system compromise when attackers leverage the elevated privileges of the Nagios service. Organizations using affected Nagios XI versions face significant risk of data exfiltration, system disruption, and potential lateral movement within their network infrastructure. The vulnerability is particularly dangerous in environments where Nagios XI serves as a central monitoring point, as it can provide attackers with visibility into network operations and potentially serve as a foothold for further attacks. According to ATT&CK framework technique T1059.001, this vulnerability enables adversaries to execute commands through the command and scripting interpreter, while T1068 highlights the potential for privilege escalation when attackers can leverage service account permissions. The impact is amplified in enterprise environments where Nagios XI might be configured with broad access permissions or integrated with other systems that could be compromised through this initial foothold.
Organizations should immediately implement mitigations including applying the official patch released by Nagios Inc. for version 5.4.13, which addresses the input validation issues in the affected components. Network segmentation and access controls should be strengthened around Nagios XI systems to limit exposure to untrusted networks, while implementing web application firewalls to detect and block malicious payloads targeting the vulnerable API endpoints. Regular security audits of monitoring systems and input validation processes should be conducted to identify similar vulnerabilities, and system administrators should monitor for unusual command execution patterns or unauthorized configuration changes. The vulnerability demonstrates the critical importance of input sanitization in web applications and highlights the need for comprehensive security testing of monitoring infrastructure, particularly in environments where these systems are exposed to external networks or have elevated privileges.