CVE-2022-23900
📋 TL;DR
This CVE describes a command injection vulnerability in the Wavlink WL-WN531P3 router's API that allows remote attackers to execute arbitrary commands via malicious POST requests to /cgi-bin/adm.cgi. Attackers can achieve full system compromise without authentication. Only users of the specific router model and firmware version are affected.
💻 Affected Systems
- Wavlink WL-WN531P3 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router takeover allowing attacker to intercept all network traffic, install persistent malware, pivot to internal networks, and use router as botnet node.
Likely Case
Router compromise leading to credential theft, DNS hijacking, man-in-the-middle attacks, and network disruption.
If Mitigated
Limited impact if router is behind firewall with restricted WAN access, though LAN-side attacks remain possible.
🎯 Exploit Status
Exploit requires simple HTTP POST request with command injection payload. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.wavlink.com/en_us/product/WL-WN531P3.html
Restart Required: Yes
Instructions:
1. Check vendor website for firmware updates. 2. Download latest firmware. 3. Access router admin interface. 4. Navigate to firmware update section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable WAN Management Access
allPrevent external access to router management interface
Access router admin panel -> Security -> Remote Management -> Disable
Network Segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Replace affected router with different model that receives security updates
- Place router behind dedicated firewall with strict inbound rules blocking all WAN access to management ports
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is M31G3.V5030.201204, device is vulnerable.Check Version:
curl -s http://router-ip/ | grep -i firmware or check admin interfaceVerify Fix Applied:
Verify firmware version has changed from vulnerable version. Test if POST requests to /cgi-bin/adm.cgi with command injection payloads still execute.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/adm.cgi
- Commands like 'wget', 'curl', or 'nc' in web logs
- Multiple failed login attempts followed by successful POST
Network Indicators:
- HTTP POST to /cgi-bin/adm.cgi with shell metacharacters
- Outbound connections from router to suspicious IPs
- DNS queries to known malicious domains
SIEM Query:
source="router_logs" AND (uri="/cgi-bin/adm.cgi" AND method="POST" AND (content="*;*" OR content="*|*" OR content="*`*"))