CVE-2018-18478 in LibreNMS
Summary
by MITRE
Persistent Cross-Site Scripting (XSS) issues in LibreNMS before 1.44 allow remote attackers to inject arbitrary web script or HTML via the dashboard_name parameter in the /ajax_form.php resource, related to html/includes/forms/add-dashboard.inc.php, html/includes/forms/delete-dashboard.inc.php, and html/includes/forms/edit-dashboard.inc.php.
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Analysis
by VulDB Data Team • 05/30/2023
The vulnerability CVE-2018-18478 represents a critical persistent cross-site scripting flaw in LibreNMS versions prior to 1.44, specifically affecting the dashboard management functionality. This vulnerability resides within the web application's handling of user input through the dashboard_name parameter in the /ajax_form.php resource, which processes form submissions for dashboard operations. The flaw is particularly dangerous because it allows remote attackers to inject malicious scripts that persist in the application's database and are executed whenever affected pages are loaded, making it a persistent XSS vulnerability rather than a reflected one.
The technical implementation of this vulnerability occurs in multiple dashboard-related include files including html/includes/forms/add-dashboard.inc.php, html/includes/forms/delete-dashboard.inc.php, and html/includes/forms/edit-dashboard.inc.php. These files fail to properly sanitize or escape user input before storing it in the database and subsequently rendering it in web pages without adequate context-based output encoding. The vulnerability stems from insufficient input validation and output encoding practices, specifically violating secure coding principles outlined in CWE-79 which addresses cross-site scripting vulnerabilities. Attackers can exploit this by crafting malicious payloads in the dashboard_name parameter that contain script tags or other malicious code, which then gets stored and executed in the context of other users' browsers when they view the dashboard.
The operational impact of this vulnerability is significant as it provides attackers with the ability to execute arbitrary JavaScript code in the context of authenticated users' browsers, potentially leading to session hijacking, privilege escalation, or data exfiltration. An attacker could create a malicious dashboard name containing a script that steals cookies or session tokens, or even redirects users to malicious sites. The persistent nature of the vulnerability means that once exploited, the malicious code remains active until manually removed from the database, potentially affecting all users who access the affected dashboard functionality. This vulnerability also aligns with ATT&CK technique T1566.001 which covers "Phishing with malicious attachments" and T1059.007 which covers "Command and Scripting Interpreter: JavaScript," as it enables attackers to leverage web-based attack vectors to execute malicious scripts within the target environment.
The vulnerability is particularly concerning in enterprise network monitoring environments where LibreNMS is commonly deployed, as it could provide attackers with access to sensitive network monitoring data and potentially escalate privileges if the application runs with elevated permissions. Mitigation strategies should include immediate upgrade to LibreNMS version 1.44 or later, which addresses this vulnerability through proper input sanitization and output encoding. Additionally, implementing proper input validation at multiple layers, including client-side and server-side, along with context-aware output encoding, would prevent similar issues. Network segmentation and monitoring for suspicious dashboard creation activities can also provide additional defense-in-depth measures. Organizations should also consider implementing web application firewalls to detect and block malicious payloads attempting to exploit this and similar vulnerabilities, while ensuring that proper security testing is conducted during application development and regular security audits are performed to identify potential injection flaws.