CVE-2020-27485
📋 TL;DR
This vulnerability in Garmin Forerunner 235 devices allows malicious ConnectIQ store applications to escape the restricted execution environment through an array index error in the ConnectIQ TVM interpreter. Successful exploitation provides arbitrary read/write access across the entire device memory space. Only users of affected Garmin Forerunner 235 devices with vulnerable firmware versions are impacted.
💻 Affected Systems
- Garmin Forerunner 235
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to execute arbitrary code, access sensitive user data (location, health metrics), and potentially use the device as a foothold for further network attacks.
Likely Case
Malicious ConnectIQ app could steal personal data, track user location, or disrupt device functionality while appearing legitimate in the app store.
If Mitigated
With proper app store vetting and user caution, risk is limited to theoretical exploitation by sophisticated attackers.
🎯 Exploit Status
Exploitation requires creating and distributing a malicious ConnectIQ application through the app store ecosystem.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.20 and later
Vendor Advisory: https://www.garmin.com/en-US/security/
Restart Required: Yes
Instructions:
1. Connect Garmin Forerunner 235 to Garmin Express software via USB
2. Check for firmware updates in Garmin Express
3. Install firmware version 8.20 or later
4. Restart device after update completes
🔧 Temporary Workarounds
Disable ConnectIQ App Installation
allPrevent installation of new ConnectIQ applications to eliminate attack vector
Remove Untrusted ConnectIQ Apps
allUninstall any ConnectIQ applications from unknown or untrusted developers
🧯 If You Can't Patch
- Only install ConnectIQ applications from trusted, verified developers with good reputation
- Regularly review and remove unused ConnectIQ applications from device
🔍 How to Verify
Check if Vulnerable:
Check device firmware version in Settings > System > About on the Garmin deviceCheck Version:
Not applicable - check via device interfaceVerify Fix Applied:
Confirm firmware version is 8.20 or higher in device settings📡 Detection & Monitoring
Log Indicators:
- Unusual memory access patterns in ConnectIQ TVM logs
- Multiple failed app validations in ConnectIQ store logs
Network Indicators:
- Suspicious data exfiltration from device to unknown endpoints
- Unexpected network connections from device
SIEM Query:
Not applicable for typical consumer device deployments