CVE-2020-15892
📋 TL;DR
This CVE describes a stack-based buffer overflow vulnerability in D-Link DAP-1520 access points. Attackers can bypass client-side password length validation to trigger buffer overflows via login parameters, potentially leading to remote code execution. All DAP-1520 devices running firmware versions before 1.10b04Beta02 are affected.
💻 Affected Systems
- D-Link DAP-1520
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full control of the device, installs persistent malware, pivots to internal network, and compromises other systems.
Likely Case
Attacker executes arbitrary code with root privileges, modifies device configuration, intercepts network traffic, or creates backdoor access.
If Mitigated
Attack fails due to patched firmware, leaving only failed login attempts in logs with no system compromise.
🎯 Exploit Status
Exploitation requires intercepting/modifying login requests but doesn't require authentication. Public research demonstrates reliable exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.10b04Beta02 or later
Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10169
Restart Required: Yes
Instructions:
1. Download firmware 1.10b04Beta02 or later from D-Link support site. 2. Log into DAP-1520 web interface. 3. Navigate to Maintenance > Firmware Upgrade. 4. Upload the new firmware file. 5. Wait for automatic reboot.
🔧 Temporary Workarounds
Disable web management interface
allDisable the vulnerable web interface entirely to prevent exploitation
Use CLI or alternative management method to disable HTTP/HTTPS management
Network segmentation
allIsolate DAP-1520 devices to prevent lateral movement if compromised
🧯 If You Can't Patch
- Segment affected devices on isolated VLAN with strict firewall rules
- Implement network-based IPS rules to detect/block exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface under Maintenance > Firmware or via SSH: cat /etc/versionCheck Version:
ssh admin@device_ip 'cat /etc/version' or check web interfaceVerify Fix Applied:
Confirm firmware version is 1.10b04Beta02 or higher in web interface or via command line📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with unusually long password fields
- Web server crash/restart logs
- Buffer overflow error messages in system logs
Network Indicators:
- HTTP POST requests to /apply.cgi with password parameter exceeding 15 characters
- Unusual outbound connections from DAP-1520 after login attempts
SIEM Query:
source="dap-1520-logs" AND (http_uri="/apply.cgi" AND http_method="POST" AND (form_data_length>1000 OR password_length>15))🔗 References
- https://research.loginsoft.com/bugs/classic-stack-based-buffer-overflow-in-dlink-firmware-dap-1520/
- https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10169
- https://research.loginsoft.com/bugs/classic-stack-based-buffer-overflow-in-dlink-firmware-dap-1520/
- https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10169
