CVE-2021-20154
📋 TL;DR
Trendnet AC2600 TEW-827DRU routers transmit sensitive information like passwords in cleartext because HTTPS is disabled by default. This affects users who haven't manually enabled HTTPS on their devices, allowing attackers on the same network to intercept credentials.
💻 Affected Systems
- Trendnet AC2600 TEW-827DRU
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers intercept administrator credentials, gain full control of the router, and potentially pivot to internal network devices or intercept all network traffic.
Likely Case
Local network attackers capture router admin credentials, modify network settings, or perform man-in-the-middle attacks on other devices.
If Mitigated
With HTTPS enabled, all web interface communications are encrypted, preventing credential interception.
🎯 Exploit Status
Exploitation requires network sniffing capabilities on the local network. No authentication bypass needed since credentials are transmitted in cleartext.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown (vendor should enable HTTPS by default in future firmware)
Vendor Advisory: https://www.trendnet.com/support/
Restart Required: No
Instructions:
1. Log into router web interface. 2. Navigate to Advanced > System > Management. 3. Enable HTTPS/SSL. 4. Save settings. 5. Always use HTTPS:// when accessing the interface.
🔧 Temporary Workarounds
Enable HTTPS manually
allManually enable HTTPS in router settings to encrypt all web interface communications
Use wired connection for configuration
allConfigure router using wired Ethernet connection to reduce wireless sniffing risk
🧯 If You Can't Patch
- Segment router management interface to separate VLAN
- Implement network monitoring for ARP spoofing and unusual traffic patterns
🔍 How to Verify
Check if Vulnerable:
Access router web interface via HTTP (not HTTPS) and check if login credentials are transmitted in cleartext using browser developer tools or network snifferCheck Version:
Check firmware version in router web interface under Status > Device InformationVerify Fix Applied:
Confirm HTTPS is enabled and all web interface communications show as encrypted/SSL in browser📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts
- Unusual configuration changes
Network Indicators:
- HTTP traffic to router management interface
- ARP spoofing detection
- Unencrypted POST requests containing 'password' fields
SIEM Query:
source_ip=router_ip AND (protocol=HTTP AND (uri_contains='login' OR uri_contains='apply.cgi'))