CVE-2023-31814
📋 TL;DR
This CVE describes a file inclusion vulnerability in D-Link DIR-300 routers that allows attackers to include arbitrary files from the filesystem via the /model/__lang_msg.php endpoint. Attackers can potentially read sensitive files, execute code, or compromise the router. All users with affected firmware versions are vulnerable.
💻 Affected Systems
- D-Link DIR-300
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete router compromise, credential theft, network pivoting, and persistent backdoor installation.
Likely Case
Sensitive file disclosure (configuration files, credentials), router configuration manipulation, and potential code execution.
If Mitigated
Limited impact if router is behind firewall with no WAN access and strong network segmentation.
🎯 Exploit Status
Exploit requires simple HTTP requests to vulnerable endpoint. Public proof-of-concept demonstrates file inclusion.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link website for latest firmware > REVA1.06 and > REVB2.06
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Visit D-Link support site. 2. Download latest firmware for your DIR-300 hardware revision. 3. Log into router admin interface. 4. Navigate to firmware update section. 5. Upload and apply new firmware. 6. Router will reboot automatically.
🔧 Temporary Workarounds
Block External Access
allConfigure firewall to block WAN access to router admin interface
Disable Remote Management
allTurn off remote management in router settings
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict firewall rules
- Replace with supported router model if firmware updates unavailable
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System or Maintenance sectionCheck Version:
Login to router web interface and check System Information pageVerify Fix Applied:
Verify firmware version is greater than affected versions after update📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /model/__lang_msg.php with file parameters
- Unusual file access patterns in router logs
Network Indicators:
- HTTP requests to router IP on port 80/443 with file inclusion patterns
- Unusual outbound connections from router
SIEM Query:
http.url:*__lang_msg.php* AND (http.uri:*file=* OR http.uri:*path=*)