CVE-2015-4387 in Password Policy Module
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in unspecified administration pages in the Password Policy module 6.x-1.x before 6.x-1.11 and 7.x-1.x before 7.x-1.11 for Drupal, when a site has a policy that uses the username constraint, allows remote attackers to inject arbitrary web script or HTML via a crafted username that is imported from an external source.
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Analysis
by VulDB Data Team • 04/07/2019
The CVE-2015-4387 vulnerability represents a critical cross-site scripting flaw within the Drupal Password Policy module affecting versions 6.x-1.x prior to 1.11 and 7.x-1.x prior to 1.11. This vulnerability specifically targets administrative pages where password policies are configured and managed, creating a significant security risk for Drupal installations that utilize username constraint policies. The flaw arises from inadequate input validation and sanitization of user-provided data when processing usernames imported from external sources, making it particularly dangerous for organizations that integrate external authentication systems or import user data from third-party services.
The technical implementation of this vulnerability stems from the module's failure to properly sanitize user input before rendering it within administrative interfaces. When administrators view imported usernames in the policy management screens, the module directly outputs user-supplied data without appropriate encoding or filtering mechanisms. This creates an ideal environment for malicious actors to inject arbitrary web scripts or HTML content that will execute in the context of other administrators' browsers. The vulnerability is particularly insidious because it leverages legitimate administrative functionality to deliver malicious payloads, making detection more challenging and exploitation more effective.
The operational impact of this vulnerability extends beyond simple data corruption or theft, as it enables attackers to escalate privileges and potentially gain full administrative control over affected Drupal sites. Remote attackers can craft malicious usernames containing script tags or other malicious content that executes when administrators view the imported user data in the administration interface. This scenario allows for session hijacking, data exfiltration, and the potential installation of backdoors or other persistent malware. The vulnerability affects organizations that rely on external user data imports, making it particularly relevant for enterprises with integrated authentication systems or those that import user accounts from legacy systems.
Organizations should prioritize immediate remediation by upgrading to the patched versions 6.x-1.11 and 7.x-1.11 of the Password Policy module, as these releases contain the necessary input sanitization and output encoding fixes. Security teams should also implement network-level monitoring to detect suspicious username imports and consider implementing additional administrative controls such as role-based access restrictions for password policy management. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1059.001 for command and scripting interpreter usage in web applications. Organizations should conduct thorough security audits of their Drupal installations to identify any other modules that might exhibit similar input validation weaknesses, as this vulnerability demonstrates the importance of proper input sanitization in administrative interfaces.