CVE-2023-41219
📋 TL;DR
This is a stack-based buffer overflow vulnerability in D-Link DIR-3040 routers that allows authenticated attackers on the local network to execute arbitrary code with root privileges. The vulnerability exists in the prog.cgi binary that handles HNAP requests on the router's web interface. Attackers must be network-adjacent and have valid credentials to exploit this vulnerability.
💻 Affected Systems
- D-Link DIR-3040
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router with root-level code execution, allowing attackers to intercept all network traffic, modify router settings, install persistent malware, and pivot to other devices on the network.
Likely Case
Router compromise leading to network traffic interception, DNS hijacking, credential theft, and potential lateral movement to connected devices.
If Mitigated
Limited impact due to authentication requirement and network adjacency requirement, though successful exploitation still yields root access.
🎯 Exploit Status
Exploitation requires authentication credentials and network adjacency. The ZDI advisory includes technical details that could facilitate weaponization.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.20B07
Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10350
Restart Required: Yes
Instructions:
1. Log into the DIR-3040 web interface. 2. Navigate to System > Firmware Update. 3. Download firmware version 1.20B07 from D-Link support site. 4. Upload and install the firmware. 5. The router will reboot automatically after installation.
🔧 Temporary Workarounds
Disable remote management
allPrevent access to the router's web interface from the local network
Change default credentials
allUse strong, unique passwords to reduce risk of credential-based attacks
🧯 If You Can't Patch
- Segment the network to isolate the DIR-3040 router from critical systems
- Implement network monitoring for unusual HNAP requests to prog.cgi
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System > Firmware Update. If version is earlier than 1.20B07, the device is vulnerable.Check Version:
No CLI command available. Must check via web interface at System > Firmware Update.Verify Fix Applied:
Confirm firmware version shows 1.20B07 or later in the router web interface.📡 Detection & Monitoring
Log Indicators:
- Unusual HNAP POST requests to /prog.cgi
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unusual traffic patterns from router to internal/external systems
- Suspicious outbound connections originating from router
SIEM Query:
source="router_logs" AND (uri="/prog.cgi" OR method="POST" AND uri CONTAINS "prog.cgi")