CVE-2018-20756 in Revolution
Summary
by MITRE
MODX Revolution through v2.7.0-pl allows XSS via a document resource (such as pagetitle), which is mishandled during an Update action, a Quick Edit action, or the viewing of manager logs.
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Analysis
by VulDB Data Team • 07/06/2023
This vulnerability exists in MODX Revolution versions up to and including v2.7.0-pl where improper input validation and output encoding creates a cross-site scripting attack vector. The flaw specifically affects document resources including pagetitle fields that are processed during update operations, quick edit functions, and manager log displays. When user-supplied data containing malicious script code is submitted and subsequently rendered without proper sanitization, attackers can execute arbitrary JavaScript in the context of other users' browsers. The vulnerability stems from insufficient sanitization of user inputs during the content management workflow where the system fails to properly escape or validate special characters that could be interpreted as executable code by web browsers.
The technical implementation of this vulnerability aligns with CWE-79 which describes cross-site scripting flaws occurring when untrusted data is sent to a web browser without proper validation or encoding. Attackers can exploit this by crafting malicious payloads in document titles or content fields that contain script tags or other malicious code sequences. When these resources are displayed in the manager interface or logged in system logs, the malicious code executes in the context of authenticated users who view the affected content. This creates a persistent threat where users with administrative privileges could be compromised, potentially leading to full system compromise through session hijacking or privilege escalation attacks.
The operational impact of this vulnerability is significant as it allows attackers to perform actions such as stealing administrator sessions, modifying content, or redirecting users to malicious sites. The vulnerability affects multiple attack surfaces within the MODX management interface including the quick edit functionality which is frequently used by administrators, making it particularly dangerous. When combined with other attack vectors, this XSS vulnerability can serve as a stepping stone for more sophisticated attacks. The persistence of the vulnerability in manager logs means that even if immediate exploitation is prevented, the malicious code can remain active in system audit trails and user interfaces. The attack surface is further expanded by the fact that this affects both the content creation and viewing processes, meaning that any user with the ability to create or edit documents can potentially introduce malicious code.
Mitigation strategies should include immediate patching of affected MODX installations to version 2.7.1 or later where the vulnerability has been addressed through proper input validation and output encoding. Organizations should implement comprehensive input sanitization at multiple layers including client-side validation, server-side filtering, and proper HTML escaping of all user-supplied content. The implementation should follow the principle of least privilege where administrators have access to only necessary functionality and where user inputs are treated as untrusted data. Security headers such as Content Security Policy should be configured to prevent execution of unauthorized scripts. Additionally, regular security audits should be conducted to identify similar vulnerabilities in custom modules or extensions that may not have been updated alongside the core platform. Organizations should also implement monitoring for suspicious activity in system logs and user interface elements where XSS attacks are most likely to occur. The vulnerability demonstrates the importance of maintaining up-to-date security practices and proper code review processes to prevent injection flaws that can lead to complete system compromise.