CVE-2020-27864
📋 TL;DR
This vulnerability allows attackers on the same network to execute arbitrary code on D-Link DAP-1860 WiFi extenders without authentication. The flaw exists in the HNAP service's improper validation of user input before executing system commands. Only D-Link DAP-1860 devices running firmware version 1.04B03 are affected.
💻 Affected Systems
- D-Link DAP-1860 WiFi Extender
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, intercept network traffic, pivot to other devices, or brick the device.
Likely Case
Attackers gain full control of the WiFi extender to monitor/modify network traffic, create backdoors, or use as a foothold for further attacks.
If Mitigated
If properly segmented and patched, impact is limited to the isolated device with no lateral movement.
🎯 Exploit Status
Exploit requires network access but no authentication. Public exploit details available in ZDI advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.04B04 or later
Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10197
Restart Required: Yes
Instructions:
1. Download latest firmware from D-Link support site. 2. Log into device web interface. 3. Navigate to Firmware Update section. 4. Upload and apply new firmware. 5. Device will reboot automatically.
🔧 Temporary Workarounds
Disable HNAP Service
allDisable the vulnerable HNAP service if not required for functionality.
Network Segmentation
allIsolate WiFi extenders on separate VLAN from critical systems.
🧯 If You Can't Patch
- Physically disconnect device from network until patched
- Implement strict firewall rules to block all traffic to port 80 on affected devices
🔍 How to Verify
Check if Vulnerable:
Check firmware version in device web interface or via SSH if enabled. Version 1.04B03 is vulnerable.Check Version:
Check web interface System Status page or use: curl -s http://device-ip/HNAP1/ | grep -i versionVerify Fix Applied:
Verify firmware version is 1.04B04 or later after update.📡 Detection & Monitoring
Log Indicators:
- Unusual HNAP service requests
- Multiple failed authentication attempts to HNAP
- System command execution logs
Network Indicators:
- Unusual HTTP POST requests to /HNAP1/ endpoint
- Traffic to port 80 from unexpected internal sources
- Command injection patterns in HTTP headers
SIEM Query:
source="dlink-extender" AND (http_uri="/HNAP1/" OR http_user_agent CONTAINS "exploit")