CVE-2016-6209 in Nagios
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Nagios.
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Analysis
by VulDB Data Team • 11/24/2022
The CVE-2016-6209 vulnerability represents a critical cross-site scripting flaw within the Nagios network monitoring system, which is widely deployed across enterprise environments for system and network monitoring. This vulnerability stems from inadequate input validation and output encoding mechanisms within the Nagios web interface, specifically affecting versions prior to 4.2.4. The flaw allows authenticated attackers with sufficient privileges to inject malicious scripts into the web application's output, potentially compromising the integrity of the monitoring environment and exposing sensitive operational data.
The technical implementation of this vulnerability occurs within the web-based configuration and reporting interfaces of Nagios, where user-supplied input is not properly sanitized before being rendered in HTML output contexts. Attackers can leverage this weakness by crafting malicious payloads that exploit the lack of proper HTML escaping mechanisms in various input fields, including host names, service descriptions, and custom variables used within the monitoring configuration. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically classified as reflected XSS when the malicious input is immediately reflected back to the user without proper sanitization. The attack vector requires an authenticated session, typically with administrator privileges, making it particularly dangerous in environments where Nagios is configured with elevated access rights for multiple users.
The operational impact of CVE-2016-6209 extends beyond simple script injection, as it can enable attackers to escalate privileges, steal session cookies, and potentially gain unauthorized access to the monitoring infrastructure. In enterprise environments where Nagios serves as a critical monitoring tool, this vulnerability could allow adversaries to manipulate monitoring data, hide malicious activities from detection, or redirect legitimate users to malicious websites. The vulnerability particularly affects organizations that rely heavily on Nagios for security monitoring, as it could be exploited to bypass security controls and maintain persistent access to monitored systems. The impact is amplified by the fact that Nagios installations often contain sensitive operational information, including system configurations, network topology details, and service availability data that could be valuable to threat actors.
Mitigation strategies for CVE-2016-6209 primarily focus on immediate patching of affected Nagios installations to version 4.2.4 or later, which includes proper input sanitization and output encoding mechanisms. Organizations should also implement network segmentation and access controls to limit the scope of potential exploitation, ensuring that only authorized personnel have administrative access to the Nagios web interface. Additional defensive measures include implementing content security policies, regular security audits of web applications, and monitoring for suspicious user activities within the monitoring environment. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059.007 (Scripting) and T1566 (Phishing), as it enables attackers to establish persistent access through malicious script injection and potentially use the compromised monitoring system to further their objectives. Organizations should also consider implementing web application firewalls and regular penetration testing to identify similar vulnerabilities in their monitoring infrastructure and ensure comprehensive protection against evolving threat landscapes.