CVE-2023-25088
📋 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 vulnerability affects Milesight UR32L routers running vulnerable firmware versions due to unsafe sprintf usage in firewall_handler_set function.
💻 Affected Systems
- Milesight UR32L
📦 What is this software?
Ur32l Firmware by Milesight
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level arbitrary code execution, enabling persistent backdoor installation, network pivoting, and data exfiltration.
Likely Case
Privileged attacker gains remote code execution on the router, potentially intercepting network traffic, modifying configurations, or using the device as a foothold into the network.
If Mitigated
Limited impact if proper network segmentation, privilege separation, and input validation are implemented to restrict HTTP access to trusted sources.
🎯 Exploit Status
Exploitation requires authenticated access with high privileges and knowledge of buffer overflow techniques to craft malicious HTTP requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Monitor Milesight security advisories for patch availability. 2. Download and install firmware update when released. 3. Reboot device after patching. 4. Verify fix using version check.
🔧 Temporary Workarounds
Restrict HTTP Access
linuxLimit HTTP management interface access to trusted IP addresses only using firewall rules.
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, using alternative management methods.
systemctl stop httpd
systemctl disable httpd
🧯 If You Can't Patch
- Implement strict network segmentation to isolate UR32L devices from critical network segments.
- Enforce principle of least privilege by restricting administrative access to only necessary personnel.
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface or SSH: cat /etc/version or show version command.Check Version:
cat /etc/versionVerify Fix Applied:
Verify firmware version is updated beyond v32.3.0.5 and test HTTP request handling for buffer overflow conditions.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to firewall_handler_set endpoint
- Multiple failed authentication attempts followed by successful login and HTTP exploitation attempts
- Process crashes or abnormal behavior in vtysh_ubus binary
Network Indicators:
- HTTP POST requests with unusually long parameters to UR32L management interface
- Traffic patterns suggesting buffer overflow exploitation attempts
SIEM Query:
source="ur32l_logs" AND (http_uri="*firewall_handler_set*" AND http_param_length>1000) OR process="vtysh_ubus" AND event="crash"