CVE-2023-25084
📋 TL;DR
This vulnerability allows authenticated attackers with high privileges to execute arbitrary code on Milesight UR32L routers by sending specially crafted HTTP requests. The buffer overflow occurs in the firewall_handler_set function due to unsafe sprintf usage. Only Milesight UR32L routers running vulnerable firmware are affected.
💻 Affected Systems
- Milesight UR32L
📦 What is this software?
Ur32l Firmware by Milesight
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level access, allowing attackers to install persistent backdoors, pivot to internal networks, or disrupt network operations.
Likely Case
Privilege escalation leading to unauthorized configuration changes, data exfiltration, or use as a foothold for lateral movement.
If Mitigated
Limited impact if proper network segmentation and privilege controls prevent high-privilege access to the vulnerable interface.
🎯 Exploit Status
Exploitation requires authenticated access with high privileges and knowledge of buffer overflow techniques.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Milesight website for firmware updates. 2. Download latest firmware. 3. Upload via web interface. 4. Apply and reboot router.
🔧 Temporary Workarounds
Restrict Management Access
linuxLimit access to router management interface to trusted IP addresses only
iptables -A INPUT -p tcp --dport 80 -s trusted_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate UR32L routers from critical systems
- Enforce least privilege access controls and monitor for unusual administrative activity
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System > Status > Firmware VersionCheck Version:
Not applicable - check via web interfaceVerify Fix Applied:
Verify firmware version is newer than v32.3.0.5 and test firewall configuration changes📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to firewall configuration endpoints
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- HTTP traffic to router management interface with unusually long parameter values
- Outbound connections from router to unexpected destinations
SIEM Query:
source="ur32l" AND (http_method="POST" AND uri="/cgi-bin/luci/admin/network/firewall" AND (param_length>1000 OR contains(param,"ip=") OR contains(param,"mac=") OR contains(param,"description=")))