CVE-2018-15713 in Nagios XI
Summary
by MITRE
Nagios XI 5.5.6 allows persistent cross site scripting from remote authenticated attackers via the stored email address in admin/users.php.
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Analysis
by VulDB Data Team • 04/12/2020
The vulnerability identified as CVE-2018-15713 represents a critical persistent cross site scripting flaw within Nagios XI version 5.5.6, a widely deployed network monitoring and management platform. This security weakness specifically affects the administrative user management functionality, where the system fails to properly sanitize user input when storing email addresses in the admin/users.php component. The vulnerability arises from inadequate input validation and output encoding mechanisms that allow malicious actors to inject malicious scripts into the application's data storage layer. Attackers with valid authentication credentials can exploit this flaw by manipulating their own user profile email address field to include malicious javascript code, which then gets stored persistently within the application's database. The stored script executes whenever other administrators or users view the affected user profile information, creating a persistent threat that can affect multiple users over time.
The technical exploitation of this vulnerability follows a well-established XSS attack pattern where the attacker leverages their authenticated access to inject malicious code that gets executed in the context of other users' browsers. This particular flaw falls under CWE-79 which specifically addresses Cross-site Scripting vulnerabilities in software applications. The persistent nature of the vulnerability means that the malicious payload remains active even after the initial injection, making it particularly dangerous as it can affect any user who views the compromised user profile information. The attack vector requires only remote authenticated access, which significantly lowers the barrier to exploitation compared to more complex attack scenarios that require additional privileges or network access.
The operational impact of CVE-2018-15713 extends beyond simple data theft or defacement, as it creates a potential entry point for more sophisticated attacks within the monitored network infrastructure. When attackers can execute arbitrary javascript code within the context of administrative sessions, they can potentially hijack user sessions, steal authentication tokens, or gain access to sensitive monitoring data that could reveal critical network vulnerabilities. This vulnerability directly impacts the integrity and confidentiality of the monitoring system, as administrators may unknowingly execute malicious code while managing user accounts. The persistence of the attack means that even after the initial injection, the threat remains active, potentially allowing attackers to maintain access to the system over extended periods. The vulnerability also represents a significant risk to the overall security posture of organizations relying on Nagios XI for critical infrastructure monitoring, as it undermines the trust model of the administrative interface.
Organizations affected by this vulnerability should immediately implement mitigation strategies including input sanitization of user profile fields, output encoding of stored data, and comprehensive security auditing of all user management components. The recommended approach involves implementing strict validation rules that prevent the injection of javascript code into email address fields, combined with proper HTML encoding of stored values before display. Security patches should be applied as soon as available from the vendor, while network segmentation and monitoring can provide additional layers of protection. The vulnerability also highlights the importance of regular security assessments of monitoring systems, as these platforms often contain sensitive information and serve as potential attack vectors for broader network compromises. Organizations should consider implementing web application firewalls and additional access controls to limit the impact of such vulnerabilities, while also ensuring that administrative interfaces are regularly audited for similar security weaknesses. This vulnerability demonstrates the critical importance of maintaining secure coding practices and input validation mechanisms in administrative web applications, as these interfaces often represent the most privileged access points within security monitoring systems.