CVE-2021-45382
📋 TL;DR
A critical Remote Command Execution vulnerability exists in multiple D-Link router models via the DDNS function in the ncc2 binary. Attackers can execute arbitrary commands with root privileges on affected devices. All listed D-Link DIR series routers are affected and have reached end-of-life, meaning no official patches will be released.
💻 Affected Systems
- D-Link DIR-810L
- D-Link DIR-820L
- D-Link DIR-820LW
- D-Link DIR-826L
- D-Link DIR-830L
- D-Link DIR-836L
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of router with root access, allowing attackers to intercept all network traffic, install persistent malware, pivot to internal network devices, and use router as botnet node.
Likely Case
Router takeover leading to DNS hijacking, credential theft from network traffic, and installation of cryptocurrency miners or botnet malware.
If Mitigated
Limited impact if router is isolated from internet or behind additional security controls, though local network compromise remains possible.
🎯 Exploit Status
Public exploit code available on GitHub. CISA lists as known exploited vulnerability. Exploitation requires network access to router's web interface or DDNS service.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10264
Restart Required: No
Instructions:
No official patch available due to EOL status. Vendor recommends replacing affected devices with supported models.
🔧 Temporary Workarounds
Disable DDNS Functionality
allTurn off Dynamic DNS service in router configuration to remove attack vector
Login to router admin interface -> Advanced -> DDNS Settings -> Disable DDNS
Block External Access to Web Interface
allConfigure firewall to block WAN access to router administration interface
In router firewall settings: Block WAN access to ports 80, 443, and 8080
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates
- Isolate routers in separate VLAN with strict network segmentation and monitoring
🔍 How to Verify
Check if Vulnerable:
Check router model and firmware version via admin interface. If model matches affected list, device is vulnerable.Check Version:
Login to router web interface and check System Status or About page for model and firmware information.Verify Fix Applied:
Verify DDNS is disabled in router settings and test with network scan for open administration ports from external network.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /ddnsmngr.cgi or ncc2 processes
- Suspicious command execution in system logs
- Failed authentication attempts to router admin interface
Network Indicators:
- Unusual outbound connections from router to unknown IPs
- DNS queries to suspicious domains
- Traffic patterns indicating command and control communication
SIEM Query:
source="router_logs" AND (uri="/ddnsmngr.cgi" OR process="ncc2") AND (cmd="*" OR shell="*")🔗 References
- https://github.com/doudoudedi/D-LINK_Command_Injection1/blob/main/D-LINK_Command_injection.md
- https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10264
- https://github.com/doudoudedi/D-LINK_Command_Injection1/blob/main/D-LINK_Command_injection.md
- https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10264
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-45382
