CVE-2024-39798
📋 TL;DR
This vulnerability allows authenticated attackers to execute arbitrary commands on Wavlink AC3000 routers by exploiting configuration injection in the OpenVPN setup functionality. Attackers can gain full control of affected devices through specially crafted HTTP requests. Only users of specific Wavlink router models with vulnerable firmware are affected.
💻 Affected Systems
- Wavlink AC3000 M33A8
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network pivoting to internal systems, credential theft, and botnet recruitment.
Likely Case
Local network compromise, router configuration manipulation, DNS hijacking, and credential harvesting from connected devices.
If Mitigated
Limited to authenticated users only, reducing attack surface to those with router admin access.
🎯 Exploit Status
Exploit requires authenticated access but is straightforward once credentials are obtained. Detailed technical analysis available in Talos report.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No vendor advisory found at time of analysis
Restart Required: Yes
Instructions:
1. Check Wavlink website for firmware updates. 2. Download latest firmware for AC3000 M33A8. 3. Backup router configuration. 4. Upload firmware via admin interface. 5. Factory reset after update. 6. Restore minimal configuration.
🔧 Temporary Workarounds
Disable OpenVPN Server
allCompletely disable OpenVPN server functionality to remove attack surface
Navigate to router admin interface > VPN > OpenVPN Server > Disable
Restrict Admin Access
allLimit admin interface access to specific IP addresses only
Navigate to router admin interface > Security > Access Control > Restrict to specific IPs
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict firewall rules
- Implement network segmentation to limit router's access to critical systems
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Status. If version is V5030.210505 or earlier, assume vulnerable.Check Version:
Login to router web interface and navigate to System Status pageVerify Fix Applied:
After firmware update, verify version is newer than V5030.210505. Test OpenVPN functionality with safe configuration.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/openvpn.cgi
- Multiple failed login attempts followed by OpenVPN configuration changes
- Commands executed via OpenVPN setup process
Network Indicators:
- Unexpected outbound connections from router
- OpenVPN configuration changes from unusual IP addresses
- Traffic patterns suggesting command and control
SIEM Query:
source="router_logs" AND (uri="/cgi-bin/openvpn.cgi" AND method="POST" AND (param="sel_open_protocol" OR size>normal))