CVE-2023-25082
📋 TL;DR
This vulnerability allows authenticated attackers with high privileges to execute arbitrary code on Milesight UR32L routers by sending specially crafted HTTP requests that trigger buffer overflows in the vtysh_ubus binary. The exploit occurs due to unsafe sprintf usage in firewall_handler_set function, affecting organizations using these routers for network infrastructure.
💻 Affected Systems
- Milesight UR32L
📦 What is this software?
Ur32l Firmware by Milesight
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attacker to install persistent backdoors, pivot to internal networks, intercept/modify network traffic, and disable security functions.
Likely Case
Privilege escalation leading to router takeover, configuration modification, credential theft, and network disruption.
If Mitigated
Limited impact due to proper network segmentation, privilege restrictions, and monitoring preventing successful exploitation.
🎯 Exploit Status
Exploitation requires authentication with high privileges. Buffer overflow in firewall_handler_set function with old_ip and old_mac variables makes reliable exploitation feasible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not publicly available
Restart Required: Yes
Instructions:
1. Check Milesight support for firmware updates. 2. Download latest firmware from vendor portal. 3. Backup current configuration. 4. Upload and install new firmware via web interface. 5. Restart router. 6. Restore configuration if needed.
🔧 Temporary Workarounds
Restrict HTTP Management Access
linuxLimit HTTP management interface access 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
Disable Unused HTTP Interface
linuxTurn off HTTP management if HTTPS is sufficient
uci set uhttpd.main.listen_http=''
uci commit uhttpd
/etc/init.d/uhttpd restart
🧯 If You Can't Patch
- Implement strict network segmentation to isolate UR32L routers from critical systems
- Enforce least privilege access controls and regularly rotate administrative credentials
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface or SSH: cat /etc/version | grep 32.3.0.5Check Version:
cat /etc/versionVerify Fix Applied:
Verify firmware version is newer than v32.3.0.5 and check for security patches in release notes📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to firewall configuration endpoints
- Multiple failed authentication attempts followed by successful login and firewall modifications
- Process crashes of vtysh_ubus binary
Network Indicators:
- HTTP POST requests with unusually long old_ip or old_mac parameters to firewall endpoints
- Traffic patterns suggesting reverse shells from router
SIEM Query:
source="router_logs" AND (uri="*firewall*" AND (param="old_ip" OR param="old_mac") AND length(param_value)>50)