CVE-2019-9166 in Nagios XI
Summary
by MITRE
Privilege escalation in Nagios XI before 5.5.11 allows local attackers to elevate privileges to root via write access to config.inc.php and import_xiconfig.php.
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Analysis
by VulDB Data Team • 08/17/2023
The vulnerability identified as CVE-2019-9166 represents a critical privilege escalation flaw within Nagios XI monitoring platform versions prior to 5.5.11. This vulnerability specifically targets local attackers who have already gained write access to certain configuration files within the system. The flaw stems from insufficient access controls and improper privilege management during the configuration import process, creating a pathway for malicious users to escalate their privileges to the root level of the system.
The technical implementation of this vulnerability involves two key files: config.inc.php and import_xiconfig.php. When a local attacker possesses write permissions to these files, they can manipulate the configuration import mechanism to execute arbitrary code with elevated privileges. The vulnerability occurs because the import_xiconfig.php script does not properly validate or sanitize input from the config.inc.php file, allowing attackers to inject malicious code that gets executed with root privileges during the configuration import process. This represents a classic privilege escalation vector where a local user with limited access can leverage a system configuration flaw to gain complete system control.
The operational impact of CVE-2019-9166 extends beyond simple privilege escalation, as it fundamentally compromises the security model of Nagios XI installations. Once an attacker achieves root access through this vulnerability, they can modify any system files, install backdoors, exfiltrate sensitive data, or completely disable monitoring capabilities. This vulnerability directly maps to CWE-269, which describes improper privilege management, and aligns with ATT&CK technique T1068, privilege escalation through local exploitation. The vulnerability is particularly dangerous in environments where Nagios XI is used for critical infrastructure monitoring, as it can lead to complete system compromise and potential lateral movement within the network.
Mitigation strategies for CVE-2019-9166 must address both immediate remediation and long-term security hardening. The primary solution involves upgrading to Nagios XI version 5.5.11 or later, which includes proper access controls and input validation for the configuration import process. System administrators should also implement strict file permission controls, ensuring that config.inc.php and import_xiconfig.php files are only writable by authorized system administrators. Additionally, implementing principle of least privilege for user accounts and regular security audits of configuration files can significantly reduce the attack surface. Network segmentation and monitoring of file system changes can provide early detection of potential exploitation attempts, while regular vulnerability assessments help identify similar privilege escalation flaws in other system components.