CVE-2018-10121 in Monstra
Summary
by MITRE
plugins/box/pages/pages.admin.php in Monstra CMS 3.0.4 has a stored XSS vulnerability when an attacker has access to the editor role, and enters the payload in the title section of an admin/index.php?id=pages&action=edit_page&name=error404 (aka Edit 404 page) action.
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Analysis
by VulDB Data Team • 02/28/2023
The vulnerability identified as CVE-2018-10121 represents a critical stored cross-site scripting flaw within Monstra CMS version 3.0.4 that specifically targets the administrative interface. This security weakness resides in the plugins/box/pages/pages.admin.php file and manifests when users with editor privileges attempt to modify the 404 error page through the administrative dashboard. The attack vector is particularly concerning because it allows authenticated attackers with limited permissions to inject malicious scripts that persist in the system's database, making the vulnerability particularly dangerous for content management systems where multiple users have varying access levels.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the CMS's page editing functionality. When administrators or editors navigate to the specific URL path admin/index.php?id=pages&action=edit_page&name=error404 to modify the error page, the system fails to properly sanitize user-supplied input from the title field before storing it in the database. This stored data is then subsequently rendered without proper HTML escaping or encoding, creating an environment where malicious JavaScript code can be executed whenever the affected page is accessed by any user, including administrators. The vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws, and represents a classic case of stored XSS where the malicious payload is permanently stored and executed during subsequent page loads.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to escalate their privileges and potentially compromise the entire CMS installation. An attacker with editor access can craft malicious payloads that might steal session cookies, redirect users to phishing sites, or even execute commands on the server if additional vulnerabilities exist. The attack scenario becomes particularly dangerous when considering that many CMS administrators may not regularly monitor all pages, especially error pages that are typically viewed only under specific circumstances. This vulnerability can be exploited to create persistent backdoors within the system, enabling long-term unauthorized access and data exfiltration. The ATT&CK framework categorizes this as a privilege escalation technique through web application vulnerabilities, where initial access with limited permissions can be leveraged to gain more significant control over the affected system.
Mitigation strategies for CVE-2018-10121 should begin with immediate patching of the Monstra CMS to version 3.0.5 or later, which contains the necessary fixes for the XSS vulnerability. Organizations should also implement comprehensive input validation and output encoding mechanisms throughout the CMS, particularly for all user-editable fields including titles, descriptions, and content areas. Regular security audits of CMS plugins and themes are essential to identify similar vulnerabilities that may exist in third-party components. Network monitoring should be enhanced to detect unusual traffic patterns that might indicate exploitation attempts, and access controls should be strictly enforced to limit administrative privileges to only trusted users. Additionally, implementing Content Security Policy headers and regular security scanning of web applications can provide additional layers of protection against similar stored XSS vulnerabilities in the future.