CVE-2020-9395
📋 TL;DR
A stack-based buffer overflow vulnerability exists in Realtek Wi-Fi chipset firmware for specific IoT devices. Attackers can exploit this by sending a specially crafted WPA2 4-way handshake packet, potentially allowing remote code execution. Affected devices include Realtek RTL8195AM, RTL8711AM, RTL8711AF, and RTL8710AF chipsets running vulnerable firmware.
💻 Affected Systems
- Realtek RTL8195AM
- Realtek RTL8711AM
- Realtek RTL8711AF
- Realtek RTL8710AF
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, credential theft, and lateral movement within the network.
Likely Case
Device crash/reboot (denial of service) or limited code execution depending on exploit sophistication.
If Mitigated
No impact if patched or if network segmentation prevents attacker access.
🎯 Exploit Status
Exploitation requires Wi-Fi proximity or network access to send malformed EAPOL-Key packets.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.6 or later
Vendor Advisory: https://www.amebaiot.com/en/security_bulletin/
Restart Required: Yes
Instructions:
1. Check device firmware version. 2. Download updated firmware from vendor. 3. Flash firmware to device following vendor instructions. 4. Reboot device.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected devices on separate VLANs to limit attack surface.
WPA3 Transition
allUpgrade to WPA3 where supported to change handshake mechanism.
🧯 If You Can't Patch
- Segment network to isolate vulnerable devices from critical systems.
- Monitor for unusual Wi-Fi handshake patterns or device crashes.
🔍 How to Verify
Check if Vulnerable:
Check firmware version on device; if below 2.0.6, it's vulnerable.Check Version:
Vendor-specific command; typically via serial console or management interface.Verify Fix Applied:
Confirm firmware version is 2.0.6 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Device crash/reboot logs
- Unusual Wi-Fi authentication failures
Network Indicators:
- Malformed EAPOL-Key packets with oversized keydata
- Abnormal 4-way handshake patterns
SIEM Query:
Search for EAPOL-Key packets with keydata length > expected threshold.🔗 References
- https://github.com/ambiot/amb1_arduino/commit/dcea55cf9775a0166805b3db845b237ecd5e74ea#diff-d06e7a87f34cc464a56799a419033014
- https://github.com/ambiot/amb1_sdk/commit/bc5173d5d4faf6829074b0f1e1b242c12b7777a3#diff-700c216fb376666eaeda0c892e8bdc09
- https://www.amebaiot.com/en/security_bulletin/
- https://github.com/ambiot/amb1_arduino/commit/dcea55cf9775a0166805b3db845b237ecd5e74ea#diff-d06e7a87f34cc464a56799a419033014
- https://github.com/ambiot/amb1_sdk/commit/bc5173d5d4faf6829074b0f1e1b242c12b7777a3#diff-700c216fb376666eaeda0c892e8bdc09
- https://www.amebaiot.com/en/security_bulletin/
