CVE-2017-6929 in Drupal
Summary
by MITRE
A jQuery cross site scripting vulnerability is present when making Ajax requests to untrusted domains. This vulnerability is mitigated by the fact that it requires contributed or custom modules in order to exploit. For Drupal 8, this vulnerability was already fixed in Drupal 8.4.0 in the Drupal core upgrade to jQuery 3. For Drupal 7, it is fixed in the current release (Drupal 7.57) for jQuery 1.4.4 (the version that ships with Drupal 7 core) as well as for other newer versions of jQuery that might be used on the site, for example using the jQuery Update module.
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Analysis
by VulDB Data Team • 02/10/2023
This vulnerability represents a critical cross site scripting flaw in jQuery libraries used by Drupal content management systems, specifically affecting versions prior to the respective security patches. The issue arises when Drupal sites make Ajax requests to untrusted domains, creating an attack vector that could be exploited by malicious actors to inject arbitrary JavaScript code into web pages viewed by users. The vulnerability's exploitation requires the presence of contributed or custom modules, which means that standard Drupal installations without additional third-party extensions remain protected. This characteristic significantly reduces the attack surface but does not eliminate the risk entirely, as many Drupal sites incorporate custom functionality or contributed modules that could serve as entry points for exploitation.
The technical flaw stems from jQuery's handling of Ajax requests when communicating with external domains, where the library fails to properly sanitize or validate data received from untrusted sources. This allows attackers to inject malicious scripts that execute in the context of the victim's browser session, potentially leading to session hijacking, data theft, or further compromise of the affected systems. The vulnerability aligns with CWE-79, which describes cross site scripting weaknesses in web applications, and demonstrates how client-side library vulnerabilities can create persistent security risks. The attack pattern follows typical XSS exploitation techniques where malicious input is not properly escaped or validated before being rendered in web pages, enabling code execution in the victim's browser context.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform actions on behalf of authenticated users, potentially leading to complete system compromise. For Drupal 8 installations, the fix was implemented through a core upgrade to jQuery 3.0, which included enhanced security measures and improved input validation mechanisms. The Drupal 8.4.0 release specifically addressed this issue by updating the core jQuery library to version 3, which incorporates better sanitization practices and improved handling of cross domain requests. For Drupal 7 users, the vulnerability was resolved through updates to the jQuery library itself, with Drupal 7.57 providing support for jQuery 1.4.4 while also ensuring compatibility with newer jQuery versions that might be installed via modules like jQuery Update.
Organizations should implement comprehensive mitigation strategies that include regular security updates, proper module vetting processes, and monitoring for unauthorized library modifications. The vulnerability's resolution through core library updates demonstrates the importance of maintaining current software versions and following security best practices. Security teams should also consider implementing content security policies and monitoring for suspicious Ajax requests to detect potential exploitation attempts. This vulnerability reinforces the principle that third-party libraries, even when seemingly benign, can introduce significant security risks when not properly maintained or updated. The incident highlights the need for organizations to maintain robust patch management processes and to understand the complete attack surface of their web applications, including all contributed modules and custom code that might interface with external libraries.