CVE-2021-43573
📋 TL;DR
A buffer overflow vulnerability in Realtek RTL8195AM Wi-Fi chips allows remote attackers to execute arbitrary code by sending specially crafted beacon or association response frames. This affects devices using Realtek RTL8195AM chips with firmware versions before 2.0.10. Attackers can exploit this without authentication over Wi-Fi range.
💻 Affected Systems
- Devices using Realtek RTL8195AM Wi-Fi chips
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, persistent backdoor installation, and lateral movement to connected networks.
Likely Case
Device crash/reboot (DoS) or limited code execution allowing network traffic interception and credential theft.
If Mitigated
No impact if patched firmware is installed and proper network segmentation is implemented.
🎯 Exploit Status
Buffer overflow in HT capability IE parsing allows straightforward exploitation. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.10 or later
Vendor Advisory: https://www.amebaiot.com/en/security_bulletin/cve-2021-43573/
Restart Required: Yes
Instructions:
1. Contact device manufacturer for updated firmware. 2. Download firmware version 2.0.10+. 3. Follow manufacturer's flashing instructions. 4. Verify firmware version after update.
🔧 Temporary Workarounds
Disable Wi-Fi client mode
allPrevent exploitation by disabling Wi-Fi client functionality if device supports alternative connectivity.
Manufacturer-specific commands to disable Wi-Fi client mode
Network segmentation
linuxIsolate affected devices on separate VLANs with strict firewall rules.
# Example: iptables -A FORWARD -s vulnerable_subnet -j DROP
🧯 If You Can't Patch
- Physically isolate devices from untrusted networks
- Implement strict network access controls and monitor for anomalous Wi-Fi traffic
🔍 How to Verify
Check if Vulnerable:
Check firmware version via manufacturer's management interface or CLI. If version < 2.0.10, device is vulnerable.Check Version:
Manufacturer-specific command (varies by device implementation)Verify Fix Applied:
Confirm firmware version is 2.0.10 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Multiple association failures
- Unexpected device reboots
- Firmware version logs showing pre-2.0.10
Network Indicators:
- Malformed HT capability IEs in beacon/association frames
- Unusual Wi-Fi traffic patterns to IoT devices
SIEM Query:
source="wifi_logs" AND (event="association_failure" OR event="device_reboot") AND device_firmware<"2.0.10"