CVE-2017-6556 in CMS Made Simple
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in CMS Made Simple (CMSMS) 2.1.6 allows remote authenticated users to inject arbitrary web script or HTML via the "adminpage > sitesetting > General Settings > globalmetadata" field.
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Analysis
by VulDB Data Team • 12/30/2019
The CVE-2017-6556 vulnerability represents a critical cross-site scripting flaw within CMS Made Simple version 2.1.6 that exposes the platform to remote exploitation by authenticated users. This vulnerability resides in the administrative interface, specifically within the global metadata configuration field, making it particularly dangerous as it allows attackers with valid administrative credentials to execute malicious scripts against other users who access the affected system. The vulnerability stems from inadequate input validation and sanitization mechanisms that fail to properly escape or filter user-supplied data before rendering it within the web application's output. The affected parameter path adminpage > sitesetting > General Settings > globalmetadata indicates that the flaw exists in the content management system's administrative configuration section where global metadata settings can be defined.
The technical implementation of this XSS vulnerability follows the standard pattern where user input flows directly into the HTML output without proper sanitization or encoding. When an authenticated administrator modifies the global metadata field, the system stores the input without sufficient validation, creating an opportunity for malicious script execution when other users browse pages that utilize this metadata. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications, and aligns with ATT&CK technique T1213 which covers data from information repositories. The vulnerability demonstrates poor input validation practices where the application fails to implement proper output encoding or content security policies that would prevent script execution in the context of the vulnerable page.
The operational impact of this vulnerability extends beyond simple script injection as it creates a persistent threat vector that can be exploited for various malicious activities including session hijacking, credential theft, and redirection to malicious sites. An attacker with administrative access can inject scripts that steal cookies, modify page content, or redirect users to phishing sites, potentially compromising the entire administrative environment. The remote nature of the attack means that even if the attacker is not physically present at the target site, they can maintain persistent access through the injected scripts. The vulnerability affects not just the immediate administrative functionality but can potentially compromise all users who view pages that utilize the compromised global metadata, making it a significant threat to the overall security posture of the CMSMS installation.
Mitigation strategies for CVE-2017-6556 should focus on immediate patching of the CMSMS platform to version 2.2.0 or later where the vulnerability has been addressed through proper input validation and sanitization. Organizations should also implement additional defensive measures including the enforcement of strict content security policies that prevent script execution, regular monitoring of administrative interfaces for unauthorized modifications, and comprehensive user access controls to limit administrative privileges to only essential personnel. The vulnerability highlights the importance of implementing proper input validation frameworks and output encoding mechanisms as recommended by OWASP top ten security practices. Security teams should also consider implementing web application firewalls that can detect and block suspicious script injection attempts, while maintaining regular security audits of administrative configurations to identify potential vulnerabilities in other areas of the CMS platform.