CVE-2023-25090
📋 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 the handle_interface_acl function. Only users of affected Milesight UR32L routers are impacted.
💻 Affected Systems
- Milesight UR32L
📦 What is this software?
Ur32l Firmware by Milesight
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level code execution, allowing attackers to install persistent backdoors, pivot to internal networks, or disrupt critical infrastructure.
Likely Case
Privileged attackers gaining remote code execution to steal credentials, modify configurations, or launch attacks against internal networks.
If Mitigated
Limited impact if proper network segmentation, privilege restrictions, and monitoring prevent exploitation attempts.
🎯 Exploit Status
Exploitation requires authenticated access with high privileges. The vulnerability is in a specific function with known buffer overflow patterns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Milesight security advisories for patch availability. 2. Download and apply firmware update when released. 3. Reboot device to activate patched firmware.
🔧 Temporary Workarounds
Network Segmentation
linuxIsolate UR32L devices from untrusted networks and restrict HTTP management interface access.
iptables -A INPUT -p tcp --dport 80 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
Privilege Restriction
allLimit administrative access to only necessary users and implement strong authentication.
🧯 If You Can't Patch
- Implement strict network access controls to limit HTTP interface exposure
- Monitor for unusual HTTP requests to vtysh_ubus endpoints and implement IDS/IPS rules
🔍 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 updated beyond v32.3.0.5 when patch becomes available📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to vtysh_ubus endpoints
- Multiple failed authentication attempts followed by interface configuration changes
Network Indicators:
- HTTP traffic to router management interface with unusually long interface or ACL parameter values
SIEM Query:
source="router_logs" AND (uri="*/vtysh_ubus*" AND (param_length>100 OR status=500))