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The Metasploit Framework

When it comes to penetration testing there are many applications available. Some can be used for footprinting and enumeration, others for gaining access to the network, and others for exploiting weaknesses in the network setup, or less than secure code. The Metasploit Framework falls into the latter category. Developed by the Metasploit Project (now acquired by Rapid7), The Metaspolit Framework is a tool that it used to run and develop exploits for penetration testing remote devices. The Metaspoit Framework is open source, and modular, allowing for the development of individual exploits, these exploits target a range of software and a range of operating systems, from The Windows family, Linux/UNIX distros and the iterations of Apples Mac OS X. There are various other free and commercial versions of Metaspolit, these include versions with GUI’s and more advanced features. This Guide however, will be based on the standard Metasploit Framework Edition, which is one of Kali Linux’s built in tools.

Various exploits with various payloads can be crafted to attack various patch versions of various software, as you see, that is a lot of variables so there is no guarantee a given exploit will be successful on a given target.

This guide however should be successful; it is a known exploit on a known target. The first thing you should do is setup a small virtual network running two VM’s. I used VirtualBox, but if you would rather use different software it shouldn’t make any difference. On the first VM install Kali Linux, this is the de facto Linux distro for penetration testing, it comes with a huge variety of tools including The Metasploit Framework. On the second VM install Metasploitable (Download here), this is a custom made Linux VM, that is designed to be used for penetration testers to hone their craft. Once you have this setup with both machines pinging each other, you are ready to go.

Step 1

The first step is to find a vulnerability that you can exploit. One of the best methods is by using nmap to scan for open ports and services that may present an open door. Namp can be run in many modes with many options, some are stealthy and will avoid Intrusion Detection Systems, some are not so stealthy, for the purpose of this guide however, we are going to run nmap in a not so stealthy fashion, purely for the purposes of demonstration. We know our target machine (as it is the only other device on our network) so we will target it directly and perform a scan that gives us a list of open ports, services running and what patch level the software is at, it will also fingerprint the target OS and give an estimation on what OS is running (it does this based on the individual nuances built in to the OS’s TCP/IP stack).

As you can see in the screenshot below, we have discovered a range of services and the versions of each service.

## -v = verbose; -A = All; this will perform a detailed scan with detailed output ##

#nmap –v –A


Step 2

The next port of call is Google. Searching for exploits via the web will give an idea of potential security vulnerabilities in the target machines software. Search for weaknesses in each individual service that you have discovered, you may find that you can get the same end result in a number of different ways, some a lot simpler than others. In our machine you will see that it is running UnrealIRC version This is popular and widely used Internet Relay Chat software. After searching the web you will discover that this version has a flaw in it that when exploited, can give an attacker root access to the Linux server running it.

Step 3

It is now time to move on to The Metasploit Framework. First, launch the tool. You will notice that the command prompt changes to the Metaspolit Framework prompt. Once the console has been launched you can use the search feature to find built in exploits, it does this by searching its database of exploit modules for the string of text you input. In this example; ‘unreal’.

This will return a list of modules that have ‘unreal’ in the title, you will find that it returns three exploits, two of which are for Unreal Tournament 2004, looking at the path you can tell there is one for Linux and one for Windows. You will also see how they are ranked, with both being ranked as good. These are not relevant to the UnrealIRC software, but the third one is. Examining the path shows that it is an exploit for UNIX systems, the correct software and the correct version of software, additionally you can see that this module is rated as excellent.

Using the info command followed by the path of the exploit will display a host of information about the module, including a description, licensing details, setting and links to references about the exploit.

[email protected]:~# msfconsole
msf > search unreal
msf > info exploit/unix/irc/unreal_ircd_3281_backdoor


Step 4

Now that we are satisfied that we have discovered an exploit module for our target software and OS, it is time to launch the module, this is done with the use command followed by the path of the exploit. Once launched the command prompt will change to the module path, you can now use context commands for that module, the show options command with display remote host IP settings and port settings.

msf > use exploit/unix/irc/unreal_ircd_3281_backdoor
msf exploit (unreal_ircd_3281_backdoor) > show options


Step 5

To set the target IP address using the set RHOST command followed by the target machines IP address. The target port will be set to the UnrealIRC default port 6667, confirm from in the information discovered with nmap that this is indeed the port being used by the service, if not use the set RPORT command to configure the target port.

msf exploit (unreal_ircd_3281_backdoor) > set RHOST
msf exploit (unreal_ircd_3281_backdoor) > set RPORT 6667

Step 6

The final step is to execute the exploit. This is done simply by using the exploit command, the screen will output information on the working of the exploit, once it is complete you should now have access as root to the target machine, confirm this by running a root level command or by using the whoami command.

msf exploit (unreal_ircd_3281_backdoor) > exploit