CVE-2017-15909 – D-Link DGS-1500 series switches have a hardcode... (How to Fix)

Q: What is the severity of CVE-2017-15909?

CVE-2017-15909 has a CVSS score of 9.8 (CRITICAL). D-Link DGS-1500 series switches have a hardcoded password that allows remote attackers to gain shell access. This affects all DGS-1500 Ax devices running firmware versions before 2.51B021. Attackers can potentially take full control of affected network switches.

📋 TL;DR

D-Link DGS-1500 series switches have a hardcoded password that allows remote attackers to gain shell access. This affects all DGS-1500 Ax devices running firmware versions before 2.51B021. Attackers can potentially take full control of affected network switches.

💻 Affected Systems

Products:

D-Link DGS-1500-20
D-Link DGS-1500-28
D-Link DGS-1500-28P
D-Link DGS-1500-52

Versions: All firmware versions before 2.51B021

Operating Systems: Embedded switch firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All DGS-1500 Ax series switches are affected. The hardcoded password is present in the firmware itself.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete compromise of network switch allowing traffic interception, network disruption, and lateral movement to other systems.

🟠

Likely Case

Unauthorized access to switch configuration, network monitoring, and potential denial of service.

🟢

If Mitigated

Limited impact if switches are isolated and access controls prevent external connections.

🌐 Internet-Facing: HIGH - Remote attackers can exploit this without authentication if switches are exposed to the internet.

🏢 Internal Only: HIGH - Even internally, any attacker on the network can exploit this vulnerability.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation requires only knowledge of the hardcoded password and network access to the switch.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 2.51B021

Vendor Advisory: ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-20/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf

Restart Required: Yes

Instructions:

1. Download firmware version 2.51B021 from D-Link support site. 2. Log into switch web interface. 3. Navigate to System > Firmware Upgrade. 4. Upload and apply the new firmware. 5. Switch will reboot automatically.

🔧 Temporary Workarounds

Network segmentation

all

Isolate DGS-1500 switches from untrusted networks and internet exposure.

Access control lists

all

Implement strict network ACLs to limit access to switch management interfaces.

🧯 If You Can't Patch

Physically isolate affected switches from internet and untrusted networks
Implement strict firewall rules to block all external access to switch management interfaces

🔍 How to Verify

Check if Vulnerable:

Check firmware version via web interface: System > Firmware Information. If version is below 2.51B021, device is vulnerable.

Check Version:

ssh admin@switch_ip show version (or via web interface)

Verify Fix Applied:

After patching, verify firmware version shows 2.51B021 or higher in System > Firmware Information.

📡 Detection & Monitoring

Log Indicators:

Failed authentication attempts followed by successful login
Unexpected SSH/Telnet connections to switch
Configuration changes from unknown sources

Network Indicators:

SSH/Telnet connections to switch from unexpected IPs
Unusual network traffic patterns from switch

SIEM Query:

source="switch_logs" (event="authentication success" AND user="admin") OR (event="configuration change" AND source_ip!="trusted_management_ip")

📊 Metadata

CVE ID: CVE-2017-15909

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-798

Published: October 26, 2017

Last Updated: April 20, 2025

🔗 References

ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-20/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-28/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-28P/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-52/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-20/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-28/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-28P/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory
ftp://ftp2.dlink.com/PRODUCTS/DGS-1500-52/REVA/DGS-1500_REVA_FIRMWARE_PATCH_NOTES_2.51.021_EN.pdf Vendor Advisory

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🔗 Related Vulnerabilities

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📋 TL;DR

💻 Affected Systems

📦 What is this software?

Dgs 1500 Firmware by Dlink

Dgs 1500 Firmware by Dlink

Dgs 1500 Firmware by Dlink

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Network segmentation

Access control lists

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities