CVE-2023-37758
📋 TL;DR
This vulnerability is a buffer overflow in D-LINK DIR-815 router firmware version 1.01, specifically in the /web/captcha.cgi component. Attackers can exploit this to execute arbitrary code or crash the device. Only users of this specific router model and firmware version are affected.
💻 Affected Systems
- D-LINK DIR-815
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full device compromise, allowing attackers to intercept traffic, modify configurations, or use the device as a pivot point into the network.
Likely Case
Denial of service causing router crashes and network disruption, potentially requiring physical reset.
If Mitigated
Limited impact if device is behind firewall with restricted web interface access and proper network segmentation.
🎯 Exploit Status
The vulnerability is in a publicly accessible CGI component and exploit details are published.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: No
Instructions:
No official patch exists. Consider replacing the device with a supported model.
🔧 Temporary Workarounds
Disable web interface
allDisable the router's web administration interface if not needed
Restrict access with firewall
linuxBlock external access to port 80/443 on the router
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace the router with a supported model that receives security updates
- Place router behind a firewall that blocks all inbound traffic to its management interface
🔍 How to Verify
Check if Vulnerable:
Check router web interface for firmware version 1.01Check Version:
curl -s http://router-ip/ | grep -i firmwareVerify Fix Applied:
Verify firmware version is no longer 1.01 or device has been replaced📡 Detection & Monitoring
Log Indicators:
- Multiple requests to /web/captcha.cgi with large payloads
- Router crash/reboot logs
Network Indicators:
- Unusual traffic patterns to router web interface
- Exploit attempt signatures in HTTP requests
SIEM Query:
source="router.log" AND (uri="/web/captcha.cgi" AND content_length>1000)