CVE-2023-25112
📋 TL;DR
This vulnerability allows authenticated attackers to execute arbitrary code on Milesight UR32L routers by exploiting buffer overflows in the vtysh_ubus binary. Attackers with high privileges can send specially crafted HTTP requests to trigger these vulnerabilities, potentially gaining full control of affected devices. This affects Milesight UR32L routers running vulnerable firmware versions.
💻 Affected Systems
- Milesight UR32L
📦 What is this software?
Ur32l Firmware by Milesight
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network pivoting, data exfiltration, and use as attack platform
Likely Case
Privileged attacker gains root access to router, modifies configurations, intercepts traffic, or installs malware
If Mitigated
Attack contained to isolated network segment with limited impact due to network segmentation and monitoring
🎯 Exploit Status
Exploitation requires authenticated access with high privileges; buffer overflow occurs in set_l2tp function with remote_subnet and remote_mask variables
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check vendor website for firmware updates
2. Download latest firmware
3. Backup current configuration
4. Upload and install new firmware
5. Restart device
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 Unnecessary Services
linuxDisable HTTP management interface if not required
systemctl stop httpd
systemctl disable httpd
🧯 If You Can't Patch
- Segment affected routers in isolated network zones
- Implement strict access controls and monitor for suspicious HTTP requests to management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface or SSH: cat /etc/versionCheck Version:
cat /etc/versionVerify Fix Applied:
Verify firmware version is updated beyond v32.3.0.5📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to management interface
- Multiple failed authentication attempts followed by successful login
- Process crashes of vtysh_ubus binary
Network Indicators:
- HTTP requests with unusually long parameters in L2TP configuration endpoints
- Traffic patterns suggesting reverse shells or command execution
SIEM Query:
source="router_logs" AND (http_uri="*set_l2tp*" AND http_param_length>1000)