How to Hack an Ethernet ADSL router?

Here’s a detailed info on how to exploit the vulnerability of an ADSL router.
Step 1: Download and install “Angry IP Scanner”
Click here to download Angry IP Scanner
Step 2: Go to http://whatismyipaddress.com. Once the page is loaded you will find your IP address. Note it down.
Step 3: Open Angry IP Scanner, here you will see an option called IP Range
Where you need to enter the range of IP address to scan for.
Suppose your IP is 184.162.195.101, you can set the range something as 184.162.194.0 to 184.162.200.255so that there exists at least 200-300 IP addresses in the range.
Step 3: Go to Tools –> Preferences and select the Ports tab. 
Under Port selection enter 80 (we need to scan for port 80). 
Now switch to the Display tab, select the option “Hosts with open ports only” and click on OK.
Hacking Ethernet ADSL router
Step 4: Now click on Start. After a few minutes, the IP scanner will show a list of IPs with Port 80 open as shown in the below image.
Hacking Ethernet ADSL router
Step 5: Now copy any of the IP from the list, paste it in your browser’s address bar and hit enter. A window will popup asking for username and password. Since most users do not change the passwords, it should most likely work with the default username and password. For most routers the default username-password pair will be admin-admin or admin-password.
Just enter the username-password as specified above and hit enter. If you are lucky you should gain access to the router settings page where you can modify any of the router settings. The settings page can vary from router to router. A sample router settings page is shown below.
Hacking Ethernet ADSL router
If you do not succeed to gain access, select another IP from the list and repeat the Step 5. At least 1 out of 5 IPs will have a default password and hence you surely will gain access.

What can an Attacker do by Gaining Access to the Router Settings?

By gaining access to the router settings, it is possible for an attacker to modify any of the router settings which results in the malfunction of the router. As a result the target user’s computer will be disconnected from the Internet. In the worst case the attacker can copy the ISP login details from the router to steal the Internet connection or play any kind of prank with the router settings. So the victim has to reconfigure the router in order to bring it back to action.

The Verdict:

If you are using an ADSL router to connect to the Internet, it is highly recommended that you immediately change your password to prevent any such attacks in the future. Who knows, you may be the next victim of such an attack.
Since the configuration varies from router to router, you need to contact your ISP for details on how to change the password for your model