CVE-2019-9123
📋 TL;DR
D-Link DIR-825 Rev.B routers have a default 'user' account with a blank password, allowing unauthorized access to the device's web interface. This affects all users of DIR-825 Rev.B routers running firmware version 2.10. Attackers can exploit this to gain administrative control over the router.
💻 Affected Systems
- D-Link DIR-825 Rev.B
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full router compromise allowing traffic interception, DNS hijacking, network pivoting, and installation of persistent malware.
Likely Case
Unauthorized access to router configuration, network reconnaissance, and potential credential theft from connected devices.
If Mitigated
Limited to attempted login failures if strong authentication is enforced.
🎯 Exploit Status
Simple web login with username 'user' and blank password. No technical skills required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch exists. Replace affected hardware or implement workarounds.
🔧 Temporary Workarounds
Change Default Password
allSet a strong password for the 'user' account via router web interface
Login to router web interface > Administration > Account Management > Change password for 'user' account
Disable Remote Management
allPrevent WAN access to router administration interface
Login to router > Tools > Admin > Disable 'Enable Remote Management'
🧯 If You Can't Patch
- Replace affected DIR-825 Rev.B router with newer model or different vendor
- Isolate router on separate VLAN with strict firewall rules limiting access
🔍 How to Verify
Check if Vulnerable:
Attempt to login to router web interface with username 'user' and blank passwordCheck Version:
Check router web interface status page or use: curl -s http://router-ip/status.html | grep FirmwareVerify Fix Applied:
Verify login fails with blank password and strong password is required📡 Detection & Monitoring
Log Indicators:
- Successful login with username 'user'
- Multiple failed login attempts followed by success
Network Indicators:
- HTTP POST requests to login.cgi with blank password parameter
- Unusual admin interface access from external IPs
SIEM Query:
source="router.log" (username="user" AND (password="" OR auth_success="true"))