Nmap Tutorial: How To Hack ADSL Router Using NMAP Tool

Asynchronous digital subscriber line (DSL or ADSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line service for connectivity to the Internet, which is often called DSL or ADSL broadband. In this guide I will show you show you how to scan IP range for connected ADSL or DSL modem routers and find DSL ADSL router hack remotely. This guide applies to Windows, Linux or Mac, so it doesn’t matter what’s your Operating system is, you can try the same steps from all these operating systems. The term DSL or ADSL modem is technically used to describe a modem which connects to a single computer, through a USB port or is installed in a computer PCI slot. The more common DSL or ADSL router which combines the function of a DSL or ADSL modem and a home router, is a standalone device which can be connected to multiple computers through multiple Ethernet ports or an integral wireless access point. Also called a residential gateway, a DSL or ADSL router usually manages the connection and sharing of the DSL or ADSL service in a home or small office network.

Put this together with Wireshark hacking for http websites, you got a nightmare for the user behind that router as all their passwords and details can be tracked very easily.

What’s in a DSL ADSL Router?

A DSL or ADSL router consists of a box which has an RJ11 jack to connect to a standard subscriber telephone line. It has several RJ45 jacks for Ethernet cables to connect it to computers or printers, creating a local network. It usually also has a USB jack which can be used to connect to computers via a USB cable, to allow connection to computers without an Ethernet port. A wireless DSL or ADSL router also has antennas to allow it to act as a wireless access point, so computers can connect to it forming a wireless network. Power is usually supplied by a cord from a wall wart transformer. It usually has a series of LED status lights which show the status of parts of the DSL or ADSL communications link:

1. Power light – indicates that the modem is turned on and has power.
2. Ethernet lights – There is usually a light over each Ethernet jack. A steady (or sometimes flashing) light indicates that the Ethernet link to that computer or device is functioning
3. DSL or ADSL light – a steady light indicates that the modem has established contact with the equipment in the local telephone exchange (DSL or ADSLAM) so the DSL or ADSL link over the telephone line is functioning
4. Internet light – a steady light indicates that the IP address and DHCP protocol are initialized and working, so the system is connected to the Internet
5. Wireless light – only in wireless DSL or ADSL modems, this indicates that the wireless network is initialized and working

Almost every ADSL DSL modem router provides a management web-page available via Internal network (LAN or Local area network) for device management, configuration and status reporting. You are supposed to login to the management web-page, configure a username password combination provided by your ISP (Internet service provider) which then allows you to connect to internet. The network is divided into two parts:

External Network

External network indicates the part where ADSL DSL modem routers connects to upstream provider for internet connectivity. Once connected to the ISP via a Phone line (ADSL DSL Modem routers can use conventional Copper Phone lines to connect to ISP at a much higher speed), the router gets an IP address. This is usually a Publicly routable IP address which is open to the whole world.

Internal Network

Internal network indicates the part where devices in Local Area Network connects to the ADSL DSL modem router via either Wireless or Ethernet cable. Most modem DSL ADSL Modem routers runs a DHCP server internally which assigns an Internall IP address to the connected device. When I say device, this can be anything from a conventional computer, a laptop, a phone (Android, Apple, Nokia or Blackberry etc.), A smart TV, A Car, NAS, SAN, An orange, A banana, A cow, A dragon, Harry Potter … I mean anything that’s able to connect to internet! So you get the idea. Each device get’s it’s own IP address, a Gateway IP and DNS entries. Depending on different DSL ADSL Modem router, this can be slightly different, but the idea remains the same, the DSL ADSL Router allows users to share internet connectivity. These DSL ADSL Modem Routers are like miniature Gateway devices that can have many services running on them. Usually they all use BusyBox or similar proprietary Linux applications on them. You want to know what a DSL ADSL Router can do? Here’s a list of common services that can run on a DSL ADSL Modem Router:

1. ADSL2 and/or ADSL2+ support
2. Antenna/ae (wireless)
3. Bridge/Half-bridge mode
4. Cookie blocking
5. DHCP server
6. DDNS support
7. DoS protection
8. Switching
9. Intrusion detection
10. LAN port rate limiting
11. Inbuilt firewall
12. Inbuilt or Free micro-filter
13. Java/ActiveX applet blocking
14. Javascript blocking
15. MAC address filtering
16. Multiple public IP address binding
17. NAT
18. Packet filter
19. Port forwarding/port range forwarding
20. POP mail checking
21. QoS (especially useful for VoIP applications)
22. RIP-1/RIP-2
23. SNTP facility
24. SPI firewall
25. Static routing
26. So-called “DMZ” facility
27. RFC1483 (bridged/routed)
28. IPoA
29. PPPoE
30. PPPoA
31. Embedded PPPoX login clients
32. Parental controls
33. Print server inbuilt
34. Scheduling by time/day of week
35. USB print server
36. URL blocking facility
37. UPnP facility
38. VPN pass-through
39. Embedded VPN servers
40. WEP 64/128/256 bit (wireless security)
41. WPA (wireless security)
42. WPA-PSK (wireless security)

That’s a lot of services running on a small device that are configured by nanny, granny, uncle, aunt and the next door neighbour, in short many non technical people around the world. How many of those configured badly? Left ports open left right and center? Didn’t change default admin passwords? Many! I mean MANY! In this guide we will use namp to scan a range of IP addresses, from output we will determine which are DSL ADSL Routers and have left their Management ports open to External Network. (again read top section to know which one is a external network). A typical ADSL Router’s Management interface is available via following URL:

http://10.0.0.1/

http://192.168.0.1/

http://192.168.1.1/

http://192.168.1.254/
etc.

This is the Management page for DSL ADSL modem router and it’s always protected by a password. By default, this password is written below a DSL ADSL modem router in a sticker and they are one of these combinations: Username/Password

admin/admin
admin/password
admin/pass
admin/secret
etc.

A lot of the home users doesn’t change this password. Well, that’s ok. It doesn’t hurt much cause this is only available via a connected device. But what’s not OKAY is when users open up their management to the external network. All you need to know what’s the Public IP address for your target and just try to access this management page externally.

Installing NMAP

I use Kali Linux which comes with NMAP Preinstalled. If you are using Windows or Mac (or any other flavour of Linux) go to the following website to download and install NMAP.

Linux Installation:

For Ubuntu, Debian or aptitude based system NMAP is usually made available via default repository. Install NMAP using the following command:

sudo apt-get install nmap

For YUM Based systems such as Redhat, CentOS, install via

sudo yum install nmap

For PACMAN based systems such as Arch Linux, install via

sudo pacman -S nmap

Windows Installation:

For Windows Computers, download installer and run the executable. Link: http://nmap.org/dist/nmap-6.46-setup.exe

Mac Installation:

For Mac users, download installer and install Link: http://nmap.org/dist/nmap-6.46.dmg

Official NMAP site

You can read more about NMAP here: http://nmap.org/

Search for Vulnerable Routers

Now that we have NMAP sorted, we are going to run the following command to scan for ADSL Modem Routers based on their Banner on Port 80 to start our ADSL router hack. All you need is to pick an IP range. I’ve used an example below using 101.53.64.1/24 range.

Search from Linux using command Line

In Linux run the following command:

nmap -sS -sV -vv -n -Pn -T5 101.53.64.1-255 -p80 -oG - | grep 'open' | grep -v 'tcpwrapped'

In Windows or Mac open NMAP and copy paste this line:

nmap -sS -sV -vv -n -Pn -T5 101.53.64.1-255 -p80 -oG -

Once it finds the results, search for the word ‘open’ to narrow down results. A typical Linux NMAP command would return outputs line below: (and of course I’ve changed the IP details)

Host: 101.53.64.3 ()  Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.4 ()  Ports: 80/open/tcp//http//micro_httpd/
Host: 101.53.64.9 ()  Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.19 () Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.20 () Ports: 80/open/tcp//http//Fortinet VPN|firewall http config/
Host: 101.53.64.23 () Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.31 () Ports: 80/open/tcp//http?///
Host: 101.53.64.33 () Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.35 () Ports: 80/open/tcp//http?///
Host: 101.53.64.37 () Ports: 80/open/tcp//http?///
Host: 101.53.64.49 () Ports: 80/open/tcp//http//Gadspot|Avtech AV787 webcam http config/
Host: 101.53.64.52 () Ports: 80/open/tcp//http?///
Host: 101.53.64.53 () Ports: 80/open/tcp//ssl|http//thttpd/
Host: 101.53.64.58 () Ports: 80/open/tcp//http?///
Host: 101.53.64.63 () Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.69 () Ports: 80/open/tcp//http//Gadspot|Avtech AV787 webcam http config/
Host: 101.53.64.73 () Ports: 80/open/tcp//http//Allegro RomPager 4.07 UPnP|1.0 (ZyXEL ZyWALL 2)/
Host: 101.53.64.79 () Ports: 80/open/tcp//http//Apache httpd/
Host: 101.53.64.85 () Ports: 80/open/tcp//http//micro_httpd/
Host: 101.53.64.107 ()        Ports: 80/open/tcp//http?///
Host: 101.53.64.112 ()        Ports: 80/open/tcp//http?///
Host: 101.53.64.115 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.123 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.129 ()        Ports: 80/open/tcp//http//Allegro RomPager 4.07 UPnP|1.0 (ZyXEL ZyWALL 2)/
Host: 101.53.64.135 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.145 ()        Ports: 80/open/tcp//http//micro_httpd/
Host: 101.53.64.149 ()        Ports: 80/open/tcp//http//Microsoft IIS httpd 6.0/
Host: 101.53.64.167 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.170 ()        Ports: 80/open/tcp//http//Allegro RomPager 4.07 UPnP|1.0 (ZyXEL ZyWALL 2)/
Host: 101.53.64.186 ()        Ports: 80/open/tcp//http?///
Host: 101.53.64.188 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.193 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.202 ()        Ports: 80/open/tcp//http//Apache httpd 2.2.15 ((CentOS))/
Host: 101.53.64.214 ()        Ports: 80/open/tcp//tcpwrapped///
Host: 101.53.64.224 ()        Ports: 80/open/tcp//http//Allegro RomPager 4.51 UPnP|1.0 (ZyXEL ZyWALL 2)/

This was taking a long time (we are after all try to scan 256 hosts using the command above). Me being just impatient, I wanted to check if my Kali Linux was actually doing anything to ADSL router hack. I used the following command in a separate Terminal to monitor what my PC was doing… it was doing a lot …

tcpdump -ni eth0

That’s a lot of connected hosts with TCP Port 80 open. Some got ‘tcpwrapped’ marked on them. It means they are possibly not accessible.

Search from Windows, Mac or Linux using GUI – NMAP or Zenmap

Assuming you got NMAP installation sorted, you can now open NMAP (In Kali Linux or similar Linux distro, you can use Zenmap which is GUI version of NAMP cross platform). Copy paste the following line in Command field

nmap -sS -sV -vv -n -Pn -T5 101.53.64.1/26 -p80 -oG -

another version of this command is using different representation of Subnet MASK.

nmap -sS -sV -vv -n -Pn -T5 101.53.64.1-255 -p80 -oG -

Press SCAN Button and wait few minutes till the scan is over.

Once you have some results, then you need to find the open devices with open ports. In search Result page:

1. Click on Services Button
2. Click on http Service
3. Click on Ports/Hosts TAB (Twice to sort them by status)

As you can see, I’ve found a few devices with open http port 80.

It is quite amazing how many devices got ports open facing outer DMZ.

Access Management Webpage

Pick one at a time. For example try this:

http://101.53.64.3

http://101.53.64.4

http://101.53.64.129

You get the idea. If it opens a webpage asking for username and password, try one of the following combinations:

admin/admin
admin/password
admin/pass
admin/secret

If you can find the Router’s model number and make, you can find exact username and password from this webpage:http://portforward.com/default_username_password/ Before we finish up, I am sure you were already impatient like me as a lot of the routers had ‘tcpwrapped’ on them which was actually stopping us from accessing the web management interface to ADSL router hack. Following command will exclude those devices from our search. I’ve also expanded my search to a broader range using a slightly different Subnet MASK.

nmap -sS -sV -vv -n -Pn -T5 101.53.64.1/22 -p80 -oG - | grep 'open' | grep -v 'tcpwrapped'

In this command I am using /22 Subnet Mask with 2 specific outputs: I am looking for the work ‘open’ and excluding ‘tcpwrapped’ on my output. As you can see, I still get a lot of outputs.

Final Words

You’ll be surprised how many have default username and passwords enabled. Once you get your access to the router, you can do a lot more, like DNS hijacking, steal username and passwords (for example: Social Media username passwords (FaceBook, Twitter, WebMail etc.)) using tcpdump/snoop on router’s interface and many more using ADSL router hack … Why did I write this guide?  Here’s one for example:

As you can see Jhefeson probably has a legitimate reason to try and reboot this shared router, but he can’t just because he doesn’t have physical access to it. If this guide works, he can actually get access back.

There’s many things you can do after you’ve got access to a router. You can change DNS settings, setup a tcpdump and later snoop all plaintext passwords using wireshark etc. If you know a friends, family. colleague or neighbor who didn’t change their routers default password, let them know of the risks.

But I am not here to judge whether it should be done or not, but this is definitely a way to gain access to a router. So hacking is not always bad, it sometime is required when you loose access or a system just wouldn’t respond. As a pentester, you should raise awareness. Share this guide as anyone who uses a Linux, Windows, Mac can use this guide to test their own network and fix ADSL router hack issue.