CVE-2021-37188
📋 TL;DR
This vulnerability allows authenticated attackers to load custom firmware on Digi TransPort devices due to insufficient bootloader verification. Attackers can change device behavior, potentially gaining full control. All Digi TransPort devices through July 21, 2021 are affected.
💻 Affected Systems
- Digi TransPort gateways
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing persistent backdoor installation, data interception, network pivoting, and disabling of legitimate functionality.
Likely Case
Unauthorized firmware modification leading to data theft, network disruption, or device repurposing for malicious activities.
If Mitigated
Limited impact with proper authentication controls, network segmentation, and monitoring preventing unauthorized access.
🎯 Exploit Status
Exploitation requires authenticated access but firmware flashing is standard functionality.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware after 2021-07-21
Vendor Advisory: https://www.digi.com/search/results?q=transport
Restart Required: Yes
Instructions:
1. Download latest firmware from Digi support portal. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot device. 5. Restore configuration if needed.
🔧 Temporary Workarounds
Restrict Management Access
allLimit administrative access to trusted networks and IP addresses only
Configure firewall rules to restrict management interface access
Strong Authentication Enforcement
allImplement complex passwords and multi-factor authentication if supported
Set strong admin passwords, disable default credentials
🧯 If You Can't Patch
- Network segmentation: Isolate affected devices in separate VLANs with strict firewall rules
- Enhanced monitoring: Implement firmware integrity checks and alert on unauthorized configuration changes
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > About) or CLI 'show version' commandCheck Version:
show version (CLI) or check System > About in web interfaceVerify Fix Applied:
Verify firmware version is newer than 2021-07-21 and bootloader verification is enabled📡 Detection & Monitoring
Log Indicators:
- Firmware upload events
- Unauthorized configuration changes
- Authentication attempts from unusual sources
Network Indicators:
- Unexpected firmware download traffic
- Management interface access from unauthorized IPs
SIEM Query:
source="digi-transport" AND (event="firmware_upload" OR event="config_change")