CVE-2018-7893 in CMS Made Simple
Summary
by MITRE
CMS Made Simple (CMSMS) 2.2.6 has stored XSS in admin/moduleinterface.php via the metadata parameter.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 01/12/2020
The vulnerability CVE-2018-7893 represents a critical stored cross-site scripting flaw discovered in CMS Made Simple version 2.2.6 within the admin/moduleinterface.php component. This vulnerability specifically affects the metadata parameter which is processed and stored within the application's database without proper sanitization or validation. The flaw allows authenticated attackers with administrative privileges to inject malicious JavaScript code that persists in the system and executes whenever the affected page is accessed by other users. The stored nature of this vulnerability means that the malicious payload remains embedded in the application's data store and can affect multiple users over time.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding mechanisms within the CMSMS administration interface. When administrators interact with module interfaces and provide metadata values, the application fails to properly sanitize these inputs before storing them in the database. This creates a persistent vector where malicious scripts can be executed in the context of other users' browsers, potentially leading to session hijacking, credential theft, or further exploitation of the compromised system. The vulnerability is classified under CWE-79 as a Cross-Site Scripting flaw, specifically demonstrating the dangerous combination of stored data processing and insufficient sanitization techniques. The attack surface is particularly concerning because it operates within the administrative interface where users have elevated privileges.
The operational impact of CVE-2018-7893 extends beyond simple script execution as it fundamentally compromises the integrity of the content management system. An attacker who successfully exploits this vulnerability can potentially escalate privileges, access sensitive administrative functions, or exfiltrate data from the CMS environment. The stored nature of the exploit means that even if the initial injection occurs during a limited time window, the malicious code continues to execute for all users accessing the affected pages until manually removed. This vulnerability particularly affects organizations that rely heavily on CMS Made Simple for their web presence, as it creates persistent attack vectors that can be leveraged for ongoing compromise of the system. The vulnerability also aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, specifically focusing on the execution of malicious scripts through web interfaces.
Mitigation strategies for CVE-2018-7893 require immediate attention and multi-layered approaches to secure the affected CMSMS installation. The primary remediation involves upgrading to CMS Made Simple version 2.2.7 or later, which includes proper input sanitization and output encoding mechanisms for metadata parameters. Organizations should also implement comprehensive input validation policies that enforce strict sanitization of all user-provided data before storage, particularly within administrative interfaces. Network-based mitigations can include web application firewalls that detect and block suspicious script payloads, though these should complement rather than replace proper application-level fixes. Security monitoring should be enhanced to detect unusual administrative activities and potential injection attempts. The vulnerability highlights the importance of maintaining current security patches and implementing proper security controls such as input validation, output encoding, and principle of least privilege access controls. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other components of the CMS ecosystem, as this type of flaw often indicates broader security weaknesses in the application architecture that may affect other input handling mechanisms.