CVE-2020-8086
📋 TL;DR
This vulnerability allows remote attackers to gain administrative privileges on Prosody XMPP servers using mod_auth_ldap or mod_auth_ldap2 modules. Attackers can impersonate local admin users by matching usernames, bypassing proper authentication checks. Systems running Prosody with these LDAP authentication modules are affected.
💻 Affected Systems
- Prosody XMPP Server with mod_auth_ldap
- Prosody XMPP Server with mod_auth_ldap2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of XMPP server with administrative control over all user accounts, message interception, server configuration changes, and potential lateral movement to connected systems.
Likely Case
Unauthorized administrative access allowing attackers to read/modify messages, impersonate users, modify server settings, and potentially access sensitive data.
If Mitigated
Limited impact if proper network segmentation, monitoring, and least privilege principles are implemented, though authentication bypass remains a critical issue.
🎯 Exploit Status
Exploitation requires valid XMPP credentials but bypasses admin privilege checks. Attackers need to know admin usernames to match them.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Modules updated after 2020-01-27
Vendor Advisory: https://prosody.im/security/advisory_20200128/
Restart Required: Yes
Instructions:
1. Update mod_auth_ldap/mod_auth_ldap2 modules to versions after 2020-01-27. 2. Restart Prosody service. 3. Verify the fix by checking module versions and testing admin functionality.
🔧 Temporary Workarounds
Disable LDAP authentication modules
allTemporarily disable vulnerable modules until patching is possible
Comment out or remove 'mod_auth_ldap' and 'mod_auth_ldap2' from prosody.cfg
Implement network restrictions
linuxRestrict XMPP server access to trusted networks only
Configure firewall rules to limit access to XMPP ports (typically 5222, 5269)
🧯 If You Can't Patch
- Implement strict network segmentation to isolate XMPP server from critical systems
- Enable detailed logging and monitoring for unusual admin activity patterns
🔍 How to Verify
Check if Vulnerable:
Check if mod_auth_ldap or mod_auth_ldap2 modules are enabled in prosody.cfg and if module files have timestamps before 2020-01-28Check Version:
grep -r 'mod_auth_ldap' /etc/prosody/ && ls -la /usr/lib/prosody/modules/auth/Verify Fix Applied:
Verify module files have been updated after 2020-01-27 and test admin functionality with non-admin users📡 Detection & Monitoring
Log Indicators:
- Unauthorized admin login attempts
- Admin actions from non-admin user accounts
- Multiple failed admin privilege escalation attempts
Network Indicators:
- XMPP authentication requests with admin usernames from unexpected sources
- Unusual admin command patterns in XMPP traffic
SIEM Query:
source="prosody.log" AND ("admin login" OR "privilege escalation" OR "unauthorized admin")🔗 References
- https://hg.prosody.im/prosody-modules/log/tip/mod_auth_ldap/mod_auth_ldap.lua
- https://hg.prosody.im/prosody-modules/log/tip/mod_auth_ldap2/mod_auth_ldap2.lua
- https://prosody.im/security/advisory_20200128/
- https://seclists.org/bugtraq/2020/Feb/5
- https://www.debian.org/security/2020/dsa-4612
- https://hg.prosody.im/prosody-modules/log/tip/mod_auth_ldap/mod_auth_ldap.lua
- https://hg.prosody.im/prosody-modules/log/tip/mod_auth_ldap2/mod_auth_ldap2.lua
- https://prosody.im/security/advisory_20200128/
- https://seclists.org/bugtraq/2020/Feb/5
- https://www.debian.org/security/2020/dsa-4612
