CVE-2018-3873
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on Samsung SmartThings Hub devices by sending an overly long secretKey value in HTTP requests. The buffer overflow in the video-core HTTP server can lead to complete system compromise. Affected users are those running the vulnerable firmware version on STH-ETH-250 hubs.
💻 Affected Systems
- Samsung SmartThings Hub STH-ETH-250
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover leading to persistent backdoor installation, credential theft, and lateral movement within the smart home network.
Likely Case
Remote code execution allowing attackers to control smart devices, intercept data, or use the hub as an attack platform.
If Mitigated
Limited impact if network segmentation prevents external access and proper monitoring detects exploitation attempts.
🎯 Exploit Status
The vulnerability requires network access to port 39500 but no authentication. Exploitation is straightforward due to the simple buffer overflow.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Later than 0.20.17
Vendor Advisory: https://www.samsung.com/us/support/answer/ANS00078095/
Restart Required: Yes
Instructions:
1. Access SmartThings Hub settings via mobile app. 2. Check for firmware updates. 3. Apply available updates. 4. Reboot the hub after update completes.
🔧 Temporary Workarounds
Network Segmentation
linuxIsolate SmartThings Hub from internet and restrict local network access
iptables -A INPUT -p tcp --dport 39500 -j DROP
🧯 If You Can't Patch
- Disable remote access features in SmartThings settings
- Place hub behind firewall with strict inbound rules blocking port 39500
🔍 How to Verify
Check if Vulnerable:
Check firmware version in SmartThings app: Settings > Hub > Firmware VersionCheck Version:
Not applicable - version check through mobile app interface onlyVerify Fix Applied:
Confirm firmware version is newer than 0.20.17 in SmartThings app📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to port 39500 with long secretKey parameters
- Crash logs from video-core process
Network Indicators:
- TCP connections to port 39500 with payloads exceeding 128 bytes in secretKey field
SIEM Query:
destination_port:39500 AND http.request.uri_query:*secretKey* AND bytes > 150