CVE-2023-39749
📋 TL;DR
CVE-2023-39749 is a critical buffer overflow vulnerability in D-Link DAP-2660 access points that allows remote attackers to execute arbitrary code or cause denial of service via a crafted GET request to the /adv_resource component. This affects D-Link DAP-2660 access points running vulnerable firmware versions. The vulnerability requires no authentication and has a CVSS score of 9.8, making it highly dangerous.
💻 Affected Systems
- D-Link DAP-2660
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement to internal networks, and persistent backdoor installation.
Likely Case
Denial of service causing device crashes and network disruption, with potential for limited code execution.
If Mitigated
Network segmentation and proper firewall rules prevent exploitation attempts from reaching vulnerable devices.
🎯 Exploit Status
Public proof-of-concept code exists in GitHub repositories, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link security bulletin for latest patched version
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Check D-Link security advisory for latest firmware. 2. Download firmware from D-Link support site. 3. Log into DAP-2660 web interface. 4. Navigate to System > Firmware Update. 5. Upload and apply new firmware. 6. Reboot device after update completes.
🔧 Temporary Workarounds
Network Segmentation
allIsolate DAP-2660 devices from untrusted networks using VLANs or firewall rules
Access Control Lists
linuxImplement firewall rules to restrict access to DAP-2660 management interfaces
iptables -A INPUT -p tcp --dport 80 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
🧯 If You Can't Patch
- Replace vulnerable DAP-2660 devices with updated models or alternative vendors
- Implement strict network segmentation and monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface at System > Firmware or via SSH: cat /etc/versionCheck Version:
curl -s http://device-ip/ | grep -i firmware || ssh admin@device-ip 'cat /etc/version'Verify Fix Applied:
Verify firmware version is updated beyond v1.13 and test /adv_resource endpoint with controlled payload📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /adv_resource with unusual parameters
- Device crash/reboot logs
- Memory corruption errors in system logs
Network Indicators:
- HTTP GET requests to /adv_resource with long parameters
- Unusual outbound connections from DAP-2660 devices
SIEM Query:
source="dlink-firewall" AND url="/adv_resource" AND (bytes>1000 OR status=500)