CVE-2021-37388
📋 TL;DR
This vulnerability is a buffer overflow in D-Link DIR-615 C2 routers that allows attackers to crash the webserver and potentially execute arbitrary code remotely. Attackers exploit the ping_ipaddr parameter in ping_response.cgi via POST requests. All users of affected router versions are at risk.
💻 Affected Systems
- D-Link DIR-615 C2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, and persistent backdoor installation.
Likely Case
Webserver crash causing denial of service and potential device reboot, with possible remote code execution in skilled attacks.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.
🎯 Exploit Status
Public proof-of-concept demonstrates exploitation. No authentication required to trigger the vulnerability via HTTP POST request.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link advisory for latest patched version
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Visit D-Link support website 2. Download latest firmware for DIR-615 C2 3. Log into router admin interface 4. Navigate to firmware update section 5. Upload and install new firmware 6. Reboot router
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router web interface
Log into router admin → Advanced → Remote Management → Disable
Block ping_response.cgi Access
linuxUse firewall rules to block access to vulnerable endpoint
iptables -A INPUT -p tcp --dport 80 -m string --string "ping_response.cgi" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict access controls
- Implement network monitoring for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under Status → Firmware. If version is 3.03WW on DIR-615 C2 hardware, device is vulnerable.Check Version:
curl -s http://router-ip/status.cgi | grep firmware_versionVerify Fix Applied:
After firmware update, verify version has changed from 3.03WW to newer version in admin interface.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /ping_response.cgi with long ping_ipaddr parameters
- Webserver crash/restart logs
Network Indicators:
- Unusual HTTP traffic to router on port 80 with POST to ping_response.cgi
- Buffer overflow patterns in HTTP requests
SIEM Query:
source="router_logs" AND (url="/ping_response.cgi" AND method="POST" AND content_length>100)