CVE-2021-27952
📋 TL;DR
The ecobee3 lite thermostat version 4.5.81.200 contains hardcoded default root credentials that allow attackers to gain privileged access through the serial console. This vulnerability affects all ecobee3 lite devices running the vulnerable firmware, enabling complete device compromise.
💻 Affected Systems
- ecobee3 lite smart thermostat
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain full root access to the device, allowing them to install persistent malware, intercept sensitive data, pivot to other network devices, or render the thermostat inoperable.
Likely Case
Local attackers with physical access or remote attackers via exposed serial interfaces can compromise the device, potentially accessing home network data and controlling HVAC systems.
If Mitigated
With proper network segmentation and physical security, risk is limited to local attackers with physical device access.
🎯 Exploit Status
Exploitation requires physical access to device's serial console interface. No authentication needed once console access obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch available. Contact ecobee support for firmware update options or replacement guidance.
🔧 Temporary Workarounds
Physical Security Controls
allRestrict physical access to thermostat devices to prevent serial console exploitation
Network Segmentation
allIsolate IoT devices on separate VLANs to limit lateral movement if compromised
🧯 If You Can't Patch
- Replace vulnerable devices with updated models from manufacturer
- Implement strict physical security controls around thermostat locations
🔍 How to Verify
Check if Vulnerable:
Check device firmware version in ecobee app or web portal. If version is 4.5.81.200, device is vulnerable.Check Version:
Not applicable - check via ecobee mobile app or web interfaceVerify Fix Applied:
Verify firmware version has been updated to a version later than 4.5.81.200📡 Detection & Monitoring
Log Indicators:
- Serial console access attempts
- Unexpected root login events
- Firmware modification logs
Network Indicators:
- Unusual outbound connections from thermostat
- Unexpected network scanning from thermostat IP
SIEM Query:
Not applicable - primarily physical access exploitation