CVE-2022-40946
📋 TL;DR
This vulnerability allows unauthenticated attackers to cause a denial of service on D-Link DIR-819 routers by sending a specially crafted request to the web interface. It affects users of DIR-819 hardware version A1 with firmware version 1.06, potentially rendering the device unresponsive.
💻 Affected Systems
- D-Link DIR-819
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device crash requiring physical power cycle, disrupting all network connectivity for connected devices
Likely Case
Router becomes unresponsive to web interface and potentially network traffic, requiring reboot
If Mitigated
No impact if device is patched or not internet-facing with proper firewall rules
🎯 Exploit Status
Simple HTTP request with malicious sys_token parameter triggers the DoS
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link advisory for latest firmware
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Visit D-Link support site 2. Download latest firmware for DIR-819 A1 3. Log into router admin 4. Navigate to firmware update section 5. Upload and apply new firmware 6. Reboot router
🔧 Temporary Workarounds
Disable remote administration
allPrevent external access to router web interface
Firewall blocking
linuxBlock access to port 80/443 on router from untrusted networks
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict access controls
- Implement network monitoring for DoS attempts against router web interface
🔍 How to Verify
Check if Vulnerable:
Check router admin interface for firmware version 1.06 and hardware version A1Check Version:
curl -s http://router-ip/ | grep -i firmwareVerify Fix Applied:
Verify firmware version is updated beyond 1.06 in router admin interface📡 Detection & Monitoring
Log Indicators:
- Multiple requests to /cgi-bin/webproc with sys_token parameter
- Router reboot events
Network Indicators:
- HTTP requests to router IP with ?getpage=html/index.html&sys_token= parameters
SIEM Query:
http.url:"/cgi-bin/webproc?getpage=html/index.html" AND http.uri.query:"sys_token="🔗 References
- http://packetstormsecurity.com/files/171484/D-Link-DIR-819-A1-Denial-Of-Service.html
- https://github.com/whokilleddb/dlink-dir-819-dos
- https://www.dlink.com/en/security-bulletin/
- http://packetstormsecurity.com/files/171484/D-Link-DIR-819-A1-Denial-Of-Service.html
- https://github.com/whokilleddb/dlink-dir-819-dos
- https://www.dlink.com/en/security-bulletin/
