CVE-2024-52523
📋 TL;DR
This vulnerability in Nextcloud Server exposes fixed credentials for external storage configurations through the API and frontend. An attacker with an active user session can read these credentials in plain text. All Nextcloud Server instances with external storage configured using fixed credentials are affected.
💻 Affected Systems
- Nextcloud Server
- Nextcloud Enterprise Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An attacker with compromised user credentials could steal external storage credentials, potentially gaining access to sensitive data stored externally and enabling lateral movement to other systems.
Likely Case
An attacker with stolen session cookies or compromised user account could harvest external storage credentials, leading to data exfiltration from connected storage services.
If Mitigated
With proper session management, strong authentication, and network segmentation, the impact is limited to credential exposure for the specific user's external storage only.
🎯 Exploit Status
Requires authenticated session access. Exploitation involves accessing the API endpoint that returns credentials.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 28.0.12, 29.0.9, 30.0.2 for Nextcloud Server; 25.0.13.14, 26.0.13.10, 27.1.11.10, 28.0.12, 29.0.9, 30.0.2 for Nextcloud Enterprise Server
Vendor Advisory: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-42w6-r45m-9w9j
Restart Required: Yes
Instructions:
1. Backup your Nextcloud instance and database. 2. Update Nextcloud via the web updater (Admin → Overview → Open updater) or manually via occ command: sudo -u www-data php occ upgrade. 3. Restart web server: sudo systemctl restart apache2 (or nginx). 4. Verify update completed successfully.
🔧 Temporary Workarounds
Disable External Storage with Fixed Credentials
linuxTemporarily disable or remove external storage configurations that use fixed credentials until patching is possible.
sudo -u www-data php occ files_external:list
sudo -u www-data php occ files_external:delete <storage_id>
Use OAuth Authentication for External Storage
allReplace fixed credentials with OAuth authentication for external storage connections where supported.
🧯 If You Can't Patch
- Implement strict session management with short timeouts and IP binding
- Monitor for unusual API access patterns to external storage endpoints
🔍 How to Verify
Check if Vulnerable:
Check if external storage with fixed credentials is configured: sudo -u www-data php occ files_external:list | grep -i 'password\|credential'Check Version:
sudo -u www-data php occ status | grep 'versionstring'Verify Fix Applied:
After update, verify version: sudo -u www-data php occ status | grep 'versionstring' and ensure it matches patched versions.📡 Detection & Monitoring
Log Indicators:
- Unusual API calls to external storage endpoints
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unexpected outbound connections to external storage services
- Unusual data transfer volumes to external storage
SIEM Query:
source="nextcloud.log" ("external" AND "storage" AND "credentials") OR ("api" AND "external_storage")