CVE-2018-15509
📋 TL;DR
Five9 Agent Desktop Plus 10.0.70 has incorrect access control in WebSocket connections, allowing unauthenticated attackers to perform denial-of-service attacks and potentially access sensitive data. This affects organizations using the vulnerable version of Five9's contact center software.
💻 Affected Systems
- Five9 Agent Desktop Plus
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of contact center operations, unauthorized access to customer data, and potential privilege escalation within the Five9 environment.
Likely Case
Denial-of-service affecting agent desktop functionality, disrupting call center operations and potentially exposing session data.
If Mitigated
Limited impact with proper network segmentation and access controls, though WebSocket vulnerabilities remain concerning.
🎯 Exploit Status
Public blog posts demonstrate exploitation techniques for WebSocket denial-of-service.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 10.0.70
Vendor Advisory: https://www.five9.com/security
Restart Required: Yes
Instructions:
1. Contact Five9 support for latest secure version. 2. Backup current configuration. 3. Install updated version. 4. Restart services. 5. Verify functionality.
🔧 Temporary Workarounds
Network Segmentation
allRestrict WebSocket traffic to trusted networks only
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="TRUSTED_NETWORK" port port="443" protocol="tcp" accept'
netsh advfirewall firewall add rule name="Restrict Five9 WS" dir=in action=allow protocol=TCP localport=443 remoteip=TRUSTED_NETWORK
WebSocket Rate Limiting
linuxImplement rate limiting on WebSocket connections
iptables -A INPUT -p tcp --dport 443 -m state --state NEW -m recent --set
iptables -A INPUT -p tcp --dport 443 -m state --state NEW -m recent --update --seconds 60 --hitcount 20 -j DROP
🧯 If You Can't Patch
- Implement strict network access controls to limit WebSocket traffic to authorized IPs only
- Deploy Web Application Firewall (WAF) with WebSocket protection rules
🔍 How to Verify
Check if Vulnerable:
Check Five9 Agent Desktop Plus version in application settings or via 'About' menu. Version 10.0.70 is vulnerable.Check Version:
Check application interface or consult Five9 documentation for version verification commands.Verify Fix Applied:
Verify version is updated beyond 10.0.70 and test WebSocket connections for proper authentication.📡 Detection & Monitoring
Log Indicators:
- Unusual WebSocket connection patterns
- Multiple failed authentication attempts on WebSocket endpoints
- High volume of WebSocket connections from single IP
Network Indicators:
- Excessive WebSocket traffic to Five9 ports
- WebSocket connections bypassing authentication
- Unusual WebSocket message patterns
SIEM Query:
source="five9_logs" AND (event_type="websocket_connection" AND auth_status="failed") OR (event_type="websocket_flood" AND threshold_exceeded="true")