CVE-2018-3875
📋 TL;DR
This critical buffer overflow vulnerability in Samsung SmartThings Hub allows remote attackers to execute arbitrary code by sending a specially crafted JSON payload with an overly long sessionToken. Affected systems are Samsung SmartThings Hub STH-ETH-250 devices running vulnerable firmware versions, potentially allowing complete device compromise.
💻 Affected Systems
- Samsung SmartThings Hub STH-ETH-250
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device takeover, lateral movement to other IoT devices, and persistent backdoor installation.
Likely Case
Remote code execution allowing attacker to control the SmartThings Hub, manipulate connected IoT devices, and access sensitive home automation data.
If Mitigated
Denial of service or limited information disclosure if exploit fails to achieve code execution.
🎯 Exploit Status
Exploit requires sending a single HTTP POST request with malicious JSON payload. No authentication required. Public exploit code available in Talos advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 0.20.18 or later
Vendor Advisory: https://www.samsung.com/us/support/answer/ANS00078095/
Restart Required: Yes
Instructions:
1. Access SmartThings Hub web interface. 2. Navigate to Settings > Hub Information. 3. Check for firmware updates. 4. Apply available update. 5. Reboot the hub after update completes.
🔧 Temporary Workarounds
Network Segmentation
allIsolate SmartThings Hub from internet and untrusted networks
Firewall Block
linuxBlock external access to port 39500/TCP
iptables -A INPUT -p tcp --dport 39500 -j DROP
🧯 If You Can't Patch
- Segment the SmartThings Hub on a dedicated VLAN with strict firewall rules
- Monitor network traffic for exploitation attempts on port 39500
🔍 How to Verify
Check if Vulnerable:
Check firmware version via SmartThings app: Settings > Hub Information > Firmware Version. If version is 0.20.17 or earlier, device is vulnerable.Check Version:
curl -X POST http://[HUB_IP]:39500/api/v1/versionVerify Fix Applied:
Verify firmware version is 0.20.18 or later. Test by attempting to send exploit payload to port 39500 - should not cause crash.📡 Detection & Monitoring
Log Indicators:
- Video-core process crashes
- Unusual HTTP POST requests to /api/v1/* on port 39500
- Large sessionToken values in JSON payloads
Network Indicators:
- HTTP POST requests to port 39500 with JSON containing sessionToken > 2000 characters
- Traffic from unexpected sources to SmartThings Hub
SIEM Query:
source="smartthings" AND (http_port=39500 AND http_method=POST AND content_length>2500)