CVE-2018-20757 in Revolution
Summary
by MITRE
MODX Revolution through v2.7.0-pl allows XSS via an extended user field such as Container name or Attribute name.
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Analysis
by VulDB Data Team • 07/06/2023
The vulnerability CVE-2018-20757 represents a cross-site scripting flaw in MODX Revolution versions up to and including v2.7.0-pl. This issue specifically affects the handling of extended user fields within the content management system, creating a pathway for malicious actors to inject persistent script code into the application's user interface. The vulnerability manifests when user-supplied data is not properly sanitized or escaped before being rendered in the web interface, particularly in contexts such as container names or attribute names where extended user information is stored and displayed.
The technical exploitation of this vulnerability occurs through the manipulation of extended user fields that are subsequently rendered in the application's administrative or user interface components. When MODX processes user input for container names or attribute names, it fails to implement adequate output encoding or sanitization measures, allowing attackers to inject malicious javascript payloads that execute in the context of other users' browsers. This flaw falls under the CWE-79 category of Cross-Site Scripting, specifically representing a persistent XSS vulnerability where the malicious code is stored server-side and executed whenever affected pages are loaded. The vulnerability is particularly concerning because it leverages legitimate user fields that are expected to contain benign data, making the attack vector more subtle and harder to detect through traditional security monitoring.
The operational impact of CVE-2018-20757 extends beyond simple script injection, as it can enable attackers to perform session hijacking, steal sensitive user credentials, redirect victims to malicious sites, or execute arbitrary commands within the context of the affected application. The vulnerability affects administrators and regular users who may encounter the malicious code while browsing user management interfaces or content containers, potentially leading to full system compromise if the attacker can escalate privileges through the compromised session. This type of vulnerability directly maps to ATT&CK technique T1566.001 for initial access through spearphishing attachments and T1071.001 for application layer protocol usage, as it enables attackers to establish persistent access through the compromised user interface components. The vulnerability also aligns with ATT&CK technique T1059.007 for command and scripting interpreter usage, as the injected scripts can execute commands on behalf of the victim.
Mitigation strategies for CVE-2018-20757 require immediate patching of the MODX Revolution application to version 2.7.1 or later, which includes proper input sanitization and output encoding for extended user fields. Organizations should implement comprehensive input validation mechanisms that sanitize all user-supplied data before storage and ensure proper HTML escaping when rendering content in user interface components. Security measures should include content security policy implementation to prevent execution of unauthorized scripts, regular security audits of user input handling mechanisms, and monitoring for suspicious patterns in user field modifications. The vulnerability highlights the importance of proper output encoding practices as outlined in OWASP Top Ten categories and demonstrates the necessity of defense-in-depth strategies that include both server-side input validation and client-side output sanitization to prevent XSS attacks. Additionally, organizations should consider implementing web application firewalls to detect and block malicious payloads attempting to exploit similar vulnerabilities in other application components.