CVE-2024-36728
📋 TL;DR
TRENDnet TEW-827DRU routers contain a stack-based buffer overflow vulnerability in the ssi binary. Authenticated attackers can exploit this by sending specially crafted POST requests to apply.cgi, potentially gaining remote code execution. This affects all users of TEW-827DRU devices up to firmware version 2.06B04.
💻 Affected Systems
- TRENDnet TEW-827DRU
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full device compromise allowing attacker to install persistent malware, intercept all network traffic, pivot to internal networks, and potentially brick the device.
Likely Case
Attacker gains shell access on the router, can modify network settings, intercept traffic, and use device as foothold for further attacks.
If Mitigated
With proper network segmentation and authentication controls, impact limited to isolated network segment.
🎯 Exploit Status
Exploit requires authenticated access but is straightforward once credentials are obtained. Public proof-of-concept available in GitHub repository.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check TRENDnet website for firmware updates
2. If update available, download and follow vendor flashing instructions
3. Factory reset after update to ensure clean configuration
🔧 Temporary Workarounds
Disable VLAN Setting Interface
allRemove or restrict access to the vulnerable VLAN setting functionality
Not applicable - requires web interface configuration
Change Default Credentials
allChange all default passwords to strong, unique credentials
Not applicable - web interface configuration
🧯 If You Can't Patch
- Segment affected routers in isolated network zone with strict firewall rules
- Implement network monitoring for suspicious POST requests to apply.cgi with vlan_setting action
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under Administration > FirmwareCheck Version:
Not applicable - check via web interface or vendor may provide CLI commandVerify Fix Applied:
Verify firmware version is newer than 2.06B04📡 Detection & Monitoring
Log Indicators:
- POST requests to /apply.cgi with action=vlan_setting and unusually long dns1/dns2 parameters
- Authentication attempts followed by buffer overflow patterns
Network Indicators:
- HTTP traffic to router on port 80/443 with POST to apply.cgi containing vlan_setting
- Unusual outbound connections from router
SIEM Query:
http.method:POST AND http.uri:"/apply.cgi" AND http.param.action:"vlan_setting" AND (http.param.dns1:* OR http.param.dns2:*)