CVE-2016-20004
📋 TL;DR
This vulnerability in Drupal's REST/JSON module allows attackers to bypass field access controls, potentially accessing or modifying restricted content. It affects Drupal 7 sites using the REST/JSON module version 7.x-1.x. The module is not covered by Drupal's official security policy, leaving sites more vulnerable.
💻 Affected Systems
- Drupal REST/JSON module
📦 What is this software?
Rest\/json by Rest\/json Project
⚠️ Risk & Real-World Impact
Worst Case
Attackers could access sensitive user data, modify critical content, or escalate privileges by bypassing all field-level access restrictions.
Likely Case
Unauthorized access to restricted content fields, potentially exposing private user information or allowing content manipulation.
If Mitigated
Limited impact if proper authentication and authorization controls are in place at higher levels, though field-level protections would still be bypassed.
🎯 Exploit Status
Exploitation requires understanding of Drupal's field access system and REST endpoints, but the vulnerability itself is straightforward to exploit once identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.x-1.6
Vendor Advisory: https://www.drupal.org/node/2744889
Restart Required: No
Instructions:
1. Update the REST/JSON module to version 7.x-1.6 or later. 2. Navigate to Drupal's module update page. 3. Apply the update. 4. Clear Drupal caches.
🔧 Temporary Workarounds
Disable REST/JSON module
linuxTemporarily disable the vulnerable module until patching is possible
drush pm-disable rest_json
Restrict REST endpoint access
allUse web server configuration to restrict access to REST endpoints
# Add appropriate restrictions to Apache/Nginx configuration for /rest/* paths
🧯 If You Can't Patch
- Implement strict network-level access controls to restrict who can reach the REST endpoints
- Enable detailed logging of all REST API access and monitor for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check if the REST/JSON module is installed and if version is 7.x-1.x (excluding 7.x-1.6+)Check Version:
drush pml | grep rest_jsonVerify Fix Applied:
Verify module version is 7.x-1.6 or later and test field access controls through REST endpoints📡 Detection & Monitoring
Log Indicators:
- Unusual REST API requests accessing restricted fields
- Multiple failed authentication attempts followed by successful field access
Network Indicators:
- Unusual traffic patterns to /rest/* endpoints
- Requests bypassing expected authentication flows
SIEM Query:
source="drupal_access_log" AND (uri_path="/rest/*" AND (user="anonymous" OR status="200"))