CVE-2023-38863
📋 TL;DR
This is a command injection vulnerability in COMFAST CF-XR11 routers that allows remote attackers to execute arbitrary commands on the device. Attackers can exploit this by manipulating the ifname and mac parameters in the web management interface. This affects all users of vulnerable COMFAST CF-XR11 routers.
💻 Affected Systems
- COMFAST CF-XR11
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full device compromise allowing attacker to install persistent backdoors, pivot to internal networks, intercept all traffic, or brick the device.
Likely Case
Attacker gains shell access to execute commands, potentially installing malware, modifying configurations, or using the device as a botnet node.
If Mitigated
If properly segmented and monitored, impact limited to the device itself with no lateral movement.
🎯 Exploit Status
Public proof-of-concept available on GitHub. Simple HTTP request with crafted parameters can trigger exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check COMFAST website for firmware updates
2. Download latest firmware
3. Access router admin interface
4. Navigate to firmware upgrade section
5. Upload and apply new firmware
6. Reboot router
🔧 Temporary Workarounds
Disable Web Management Interface
linuxDisable the vulnerable web management interface if not needed
# Requires SSH/telnet access to router
# Disable webmgnt service if possible
# killall webmgnt
# rm /bin/webmgnt
Network Segmentation
linuxIsolate router from internet and sensitive networks
# Configure firewall rules to block external access to router management interface
# iptables -A INPUT -p tcp --dport 80 -j DROP
# iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Segment the router on isolated VLAN with strict firewall rules
- Implement network monitoring for suspicious traffic to/from router
🔍 How to Verify
Check if Vulnerable:
Test by sending crafted HTTP request with command injection payload to router's web interface. Check if commands execute.Check Version:
ssh admin@router 'cat /etc/version' or check web interface admin pageVerify Fix Applied:
Attempt exploitation after applying firmware update. Verify webmgnt binary has been updated.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Web server logs showing suspicious ifname/mac parameters
- Failed authentication attempts to web interface
Network Indicators:
- HTTP requests with shell metacharacters in parameters
- Outbound connections from router to suspicious IPs
- Unexpected port scans originating from router
SIEM Query:
source="router_logs" AND ("ifname=" OR "mac=") AND ("|" OR ";" OR "$" OR "`")