CVE-2012-4490 in Excluded Users
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in the Excluded Users module 6.x-1.x before 6.x-1.1 for Drupal allow remote attackers to inject arbitrary web script or HTML via a (1) user name or (2) email address.
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Analysis
by VulDB Data Team • 02/05/2018
The vulnerability identified as CVE-2012-4490 represents a critical cross-site scripting flaw within the Excluded Users module for Drupal version 6.x-1.x prior to 6.x-1.1. This module, designed to manage user exclusions and access controls within Drupal installations, contained insufficient input validation mechanisms that allowed malicious actors to inject arbitrary web scripts or HTML content. The vulnerability specifically affects the handling of user name and email address fields, creating potential attack vectors that could be exploited by remote attackers without requiring any privileged access or authentication.
The technical implementation of this vulnerability stems from inadequate sanitization of user-provided input within the Excluded Users module's processing logic. When users submitted data through the module's interface, particularly when entering names or email addresses, the application failed to properly encode or validate these inputs before storing or displaying them. This lack of input sanitization creates a classic XSS attack scenario where malicious code can be executed within the context of other users' browsers. The vulnerability operates at the application layer and specifically targets the module's user interface components that display user information, making it particularly dangerous in multi-user environments where administrators might view lists of excluded users.
The operational impact of CVE-2012-4490 extends beyond simple script injection, as it provides attackers with potential pathways for more sophisticated attacks within the Drupal environment. An attacker could craft malicious user names or email addresses containing JavaScript payloads that would execute when other administrators or users viewed the excluded users list. This could lead to session hijacking, credential theft, or further exploitation of the Drupal installation. The vulnerability is particularly concerning because it affects the administrative functionality of the system, potentially allowing attackers to compromise user accounts or gain unauthorized access to sensitive user management features. The attack requires no special privileges and can be executed remotely, making it a significant threat to Drupal installations using the affected module version.
Security professionals should recognize this vulnerability as aligning with CWE-79, which specifically addresses cross-site scripting flaws in web applications. The attack pattern corresponds to the ATT&CK technique T1059.007 for command and control through web shells, as the injected scripts could serve as entry points for more comprehensive attacks. Organizations should immediately implement the vendor-provided patch that updates the Excluded Users module to version 6.x-1.1 or higher, which includes proper input validation and sanitization measures. Additional mitigations include implementing content security policies, regular security audits of contributed modules, and ensuring that all Drupal core and contributed modules are kept current with security updates. The vulnerability demonstrates the critical importance of validating and sanitizing all user inputs, particularly in administrative modules that handle sensitive user data, and underscores the necessity of maintaining comprehensive security monitoring for web application components.