CVE-2016-3162 in Drupal
Summary
by MITRE
The File module in Drupal 7.x before 7.43 and 8.x before 8.0.4 allows remote authenticated users to bypass access restrictions and read, delete, or substitute a link to a file uploaded to an unprocessed form by leveraging permission to create content or comment and upload files.
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Analysis
by VulDB Data Team • 10/05/2018
The vulnerability described in CVE-2016-3162 represents a critical access control flaw within Drupal's File module that affects versions prior to 7.43 and 8.0.4. This issue stems from inadequate validation of file access permissions within the content management system, creating a pathway for authenticated attackers to circumvent intended security controls. The vulnerability specifically targets scenarios where users possess permissions to create content or submit comments while also having the ability to upload files, exploiting a logical flaw in how Drupal handles file references in unprocessed forms.
The technical implementation of this vulnerability occurs through a flaw in the file access checking mechanism that fails to properly validate whether authenticated users have legitimate access rights to specific files within the system. When users upload files through forms that have not yet been processed or saved, the system does not adequately verify that the requesting user has the appropriate permissions to access the file in question. This creates a situation where an attacker with minimal privileges can manipulate file references and gain unauthorized access to files that should otherwise be restricted to specific user groups or roles.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Drupal for content management, as it enables attackers to potentially access sensitive files, including user uploads, system configurations, or proprietary content. The impact extends beyond simple information disclosure, as attackers can also delete files or substitute them with malicious content, potentially leading to data corruption or system compromise. The vulnerability is particularly concerning because it requires only basic user privileges to exploit, making it accessible to anyone with legitimate access to the Drupal system who can create content or submit comments.
The flaw aligns with CWE-285, which addresses insufficient authorization in software systems, and can be mapped to ATT&CK technique T1078 for valid accounts and T1566 for credential access through social engineering. Organizations should immediately apply the security patches released by Drupal for versions 7.43 and 8.0.4, which address the file access control bypass by implementing proper permission checks during file operations. Additionally, administrators should review user permissions and implement the principle of least privilege, ensuring that users only receive the minimum necessary access rights. Network monitoring should be enhanced to detect suspicious file access patterns, and regular security audits should verify that file access controls remain properly configured. The vulnerability demonstrates the critical importance of proper access control validation in web applications, particularly when handling user-uploaded content that may be referenced across different system components.