CVE-2018-20675
📋 TL;DR
This vulnerability allows attackers to bypass authentication on affected D-Link router models, potentially gaining administrative access without valid credentials. It affects multiple D-Link DIR series routers running specific firmware versions. Attackers could exploit this to reconfigure devices, intercept traffic, or launch further attacks.
💻 Affected Systems
- D-Link DIR-822 C1
- D-Link DIR-822-US C1
- D-Link DIR-850L A*
- D-Link DIR-850L B*
- D-Link DIR-880L A*
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router compromise allowing attacker to reconfigure network settings, intercept all traffic, install malware, and use the router as a pivot point for attacking internal network devices.
Likely Case
Unauthorized administrative access leading to DNS hijacking, network configuration changes, or credential theft from connected devices.
If Mitigated
Limited impact if router is behind additional firewalls, has strong network segmentation, and regular monitoring detects unauthorized configuration changes.
🎯 Exploit Status
Authentication bypass vulnerabilities in network devices are commonly exploited. The high CVSS score and public advisory make weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: DIR-822 C1: v3.11B01Beta or later, DIR-822-US C1: v3.11B01Beta or later, DIR-850L A*: v1.21B08Beta or later, DIR-850L B*: v2.22B03Beta or later, DIR-880L A*: v1.20B02Beta or later
Vendor Advisory: https://securityadvisories.dlink.com/announcement/publication.aspx?name=SAP10101
Restart Required: Yes
Instructions:
1. Visit D-Link support website for your specific model. 2. Download the latest firmware version. 3. Log into router admin interface. 4. Navigate to firmware update section. 5. Upload and install the new firmware. 6. Wait for router to reboot automatically.
🔧 Temporary Workarounds
Disable Remote Management
allPrevents external attackers from accessing the router's web interface from the internet
Network Segmentation
allPlace router in isolated network segment to limit potential damage if compromised
🧯 If You Can't Patch
- Replace affected routers with newer models or different vendors that receive security updates
- Implement strict network monitoring for unauthorized configuration changes and unusual traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System or Maintenance section. Compare with affected versions listed in advisory.Check Version:
Log into router web interface and navigate to System Status or Firmware Information pageVerify Fix Applied:
After updating, verify firmware version shows patched version. Test authentication by attempting to access admin interface with invalid credentials (should be denied).📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts followed by successful login from same IP
- Configuration changes from unexpected IP addresses
- Admin interface access from external IPs if remote management disabled
Network Indicators:
- Unusual outbound traffic from router
- DNS configuration changes
- New port forwards or firewall rules
SIEM Query:
source="router_logs" AND (event="login_success" AND NOT user="admin") OR (event="config_change" AND src_ip NOT IN internal_range)