CVE-2023-6874
📋 TL;DR
CVE-2023-6874 is a denial of service vulnerability in Silicon Labs Ember ZNet wireless networking stack versions before 7.4.0. Attackers can manipulate NWK sequence numbers to cause network disruption or device crashes. This affects IoT devices using Ember ZNet for Zigbee/Thread networking.
💻 Affected Systems
- Silicon Labs Ember ZNet wireless networking stack
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete network disruption rendering IoT devices unresponsive, requiring physical reset or network reconfiguration.
Likely Case
Temporary network instability causing intermittent device disconnections and degraded performance.
If Mitigated
Minimal impact with proper network segmentation and monitoring detecting anomalous sequence number patterns.
🎯 Exploit Status
Attack requires network access but no authentication. Sequence number manipulation is straightforward for attackers with network visibility.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.4.0 and later
Vendor Advisory: https://community.silabs.com/069Vm000000WXaOIAW
Restart Required: Yes
Instructions:
1. Update to Ember ZNet SDK version 7.4.0 or later. 2. Recompile firmware with updated SDK. 3. Deploy updated firmware to affected devices. 4. Restart devices to apply changes.
🔧 Temporary Workarounds
Network Segmentation
allIsolate IoT networks from general corporate networks to limit attack surface
Traffic Monitoring
allMonitor for anomalous NWK sequence number patterns in network traffic
🧯 If You Can't Patch
- Implement strict network access controls to limit who can communicate with IoT devices
- Deploy network monitoring to detect and alert on sequence number manipulation attempts
🔍 How to Verify
Check if Vulnerable:
Check Ember ZNet SDK version in device firmware. Versions below 7.4.0 are vulnerable.Check Version:
Device-specific command varies by manufacturer. Typically requires accessing device management interface or checking firmware version.Verify Fix Applied:
Confirm device is running firmware compiled with Ember ZNet SDK 7.4.0 or later.📡 Detection & Monitoring
Log Indicators:
- Unexpected device resets
- Network join failures
- Sequence number anomalies in network logs
Network Indicators:
- Unusual NWK sequence number patterns
- Excessive network layer retransmissions
- Abnormal network traffic to IoT devices
SIEM Query:
Search for: device_type="IoT" AND (event_type="reset" OR event_type="disconnect") AND protocol="Zigbee" OR protocol="Thread"