D-Link Router Security Alert: Discover How to Fix DIR-816 Command Injection Vulnerability

Are you a D-Link DIR-816 router user? A serious security flaw has been discovered. This article breaks down the vulnerability—command injection—how it can be exploited, and what you can do to safeguard your home network. Learn to protect your router from unauthorized access and maintain a secure online experience.

Is Your D-Link DIR-816 Router at Risk? Command Injection Explained

The D-Link DIR-816 router, specifically the A2 V1.1.0B05 firmware version, is vulnerable to a command injection flaw. This vulnerability resides in the /goform/delRouting component of the web interface.

• What's the Threat? Remote attackers can use this vulnerability to execute arbitrary shell commands on your router.
• How Does It Work? By manipulating the DR0 parameter, attackers can inject malicious commands into the system.
• The Impact? A compromised router can lead to data theft, network disruption, or even use in larger attacks.

Vulnerability Deep Dive: Unpacking the Command Injection

The vulnerability lies within the /goform/delRouting function responsible for deleting routing rules. Let's break down how attackers exploit this flaw:

1. Parameter Control: Attackers gain control over the Var parameter by manipulating DR0.
2. String Splitting: The program divides Var into three parts (v11, v12, v13) and passes them to the sub_428FF0 function.
3. Command Construction: The sub_428FF0 function concatenates these parts into a "route del" command.
4. Execution: The doSystem function executes this constructed command, using attacker-controlled input from Var as a parameter.

This direct execution of user-supplied input—that is unfiltered—is the root cause of the command injection issue.

Real-World Example: Exploiting the D-Link DIR-816 Vulnerability

Here's a practical example of how an attacker could exploit this vulnerability to remotely reboot your D-Link DIR-816 router:

1. Obtain Token ID: Attackers first retrieve the tokenid from the router's login page using a command like curl http://192.168.0.1/dir_login.asp | grep tokenid.

2. Craft Malicious Request: Using the tokenid, they send a POST request to /goform/delRouting with a crafted DR0 parameter containing the reboot command. Here's an example Python script:

   import requests
   tokenid = '' # Replace with the actual token ID
   url = 'http://192.168.0.1/goform/delRouting'
   data = {
   'tokenid': tokenid,
   'DR0': f'a`reboot` b c'
   }
   r = requests.post(url, data)
   

   Copy

   This injected command executes a router reboot, demonstrating the potential for arbitrary code execution.

How to Protect Your D-Link Router from Command Injection Attacks

Unfortunately, there is no readily available patch for this older firmware. However, here are crucial steps you can take to mitigate the risks associated with command injection vulnerabilities and enhance your D-Link DIR-816 router security:

• Strong Password: Ensure you have a strong, unique password for your router's admin interface. Default credentials are prime targets for attackers.
• Disable Remote Access: If you don't need to access your router's settings remotely, disable remote administration to minimize the attack surface.
• Network Segmentation: Isolate sensitive devices on a separate network segment to limit the impact of a potential router compromise.
• Consider Router Upgrade: Given the lack of updates for this older model, consider upgrading to a newer router with updated security features and ongoing support.

Is Your Router a Security Risk? Understand the Importance of Router Security

This D-Link DIR-816 vulnerability highlights the critical importance of router security. Routers act as the gateway to your home network, and a compromised router can expose all connected devices to various online threats. Regularly reviewing security practices is essential. Keep your router's firmware updated and implement robust security measures to protect your digital life. Don't let command injection or other vulnerabilities compromise your network.