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Powercat

Website

https://github.com/besimorhino/powercat

Description

Powercat is a PowerShell implementation of netcat. This PowerShell module offers all the functionality of netcat with a few added features. In this lab, we'll do a series of exercises which covers the most common use cases of powercat. If you finish these exercises early, there's some bonus questions to do. Do not worry if you cannot get to them during class. Feel free to answer them later when you are going through the materials after the class has completed. Also, this lab has a challenges section. You don't have to ever do these, but they can be exceptionally rewarding and interesting to try!

Video Walkthrough

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Example 1: Setup

NOTE: You must have Windows 7 or more recent to complete this lab. If you have Windows XP, you will not be able to do this lab. While licensing prevents SANS from distributing copies of Windows to those that don't have it (I.E. those with Mac or Linux systems) we can direct you to a free for use copy of Windows. This is a limited use VM. It cannot be used for profit, and is only good for 30 days. Please read the licensing information at the site above for more information and important details. https://www.modern.ie/en-us/virtualization-tools#downloads

Launch an Administrative PowerShell prompt. To do this press your start button and type PowerShell. Right click on the PowerShell icon and select "Run as Administer".

Depending on your how your Window OS is configured, you may have to click "Accept" to run the program as Administrator. This is typical behavior for UAC.

Note: You can make sure it is an Administrator prompt by checking to see "Administrator" in the title bar. If you don't see "Administrator" somewhere in the title bar on the PowerShell window on your computer, please close this window and be sure to right click "run as Administrator"

Note the "Administrator" in the upper left corner.

Example 2: Verify Your Setup

From your Windows machine, ping the Linux VM.

PS: ping XXX

From the Linux VM, ping your Windows machine.

$ ping XXX

(reminder: in the Linux VM, you'll need to press CTRL+c to stop the pinging)

Example 3: Change the Execution Policy and Import Powercat

Check to see what your PowerShell script execution policy is.

In the PowerShell prompt, type

Get-ExecutionPolicy and hit enter

In a moment, we are going to be changing this value. So you know what to return to, please write down what your execution policy is.

Now that you have written what your policy is, you can change your execution policy.

Change your execution restriction policy to 'unrestricted' with this command:

Set-ExecutionPolicy unrestricted

If you get a prompt warning asking you if you really want to do this, please hit the 'Y' key and then hit enter

WARNING: this setting does have a security risk. In this case, any PowerShell scripts will run. Which is likely not what you actually want to happen. However, for the purposes of this lab, we're making this change so it's easier to get things running.

Now we need to invoke the powecat module so it will run from our administrative PowerShell prompt. To do this cd into the directory where the powercat script is located.

PS: cd C:\tools\

PS: Import-Module powercat.ps1

Now that powercat is loaded in this PowerShell prompt, you will be able to execute powercat commands directly from the command line interface. If you want to go back and redo these labs at a later date, you will almost certainly have to re-import the powercat

Note: It's important to note that in the interest of time, we're going to skip the element of context with PowerShell. There should be a book written on this complex topic. The reason it's critical to know at least a little bit about context with PowerShell is it controls where and how scripts and modules can be run. If you want to run powercat from another PowerShell prompt, you MUST import the powercat module like you did above or it will not be recognized by PowerShell as a command it can run.

Now that you have powercat imported, it's time to get started doing something useful.

Example 4: Common Powercat Tasks - Chat Mode

In the Linux VM open a terminal and type the following:

$ nc -l 8080

In the Windows system, in the PowerShell prompt, enter the following:

powercat -c YOUR_LINUX_IP -p 8080

While still in the PowerShell prompt, you can now type some text and hit enter.

Testing enter

From our Windows system:

From our Linux system

If all went well, you should see your text appear in the Linux terminal.

Note: you must hit enter to send the text.

Have fun with this for a few moments. You can keep sending text back and forth from one terminal to the PowerShell prompt. When you've had your fill of typing text back and forth, hit CTRL+C to end the powercat chat session.

Example 5: Common Powercat Tasks - File Transfers

One of the nicer features of netcat type tools, is the ability to move files back and forth. Depending on the firewall(s) between the hosts, may need to push files or pull files.

Setting up the listener:

on the Linux VM, type the following:

$ echo "this is my data to move" > movefile.txt

$ nc XXXIP 8888 < movefile.txt

What we've done is create a netcat listener that will stream the contents of movefile.txt to any client that connects to it.

Setting up the client:

on you windows system, enter the following in your powershell prompt:

PS:> powercat -l -p 8888 -of C:\tools\received.txt

Shutting down the listener:

On the Linux VM, shut down the listener by entering CTRL+C in the terminal you used to start the file push.

Example 6: Common Powercat Tasks - Pull a File from Windows

On your windows system enter the following at your powershell prompt

PS: echo "this is some other text to send" > win_move.txt

PS: powercat -l -p 7777 -in win_move.txt

(note: that's a lowercase L in the line above. Like PowerShell, powercat is not case sensitive. So you can use whatever case you'd like.)

Example 7: Common Powercat Tasks - Powercat Relay

This is perhaps the most powerful mode of operation for powercat. This allows you to create a pivot. Say you have three computers. A, B, and C. A and C cannot talk to eachother due to firewall restrictions. A and B can talk, B and C can talk. If we're on host A, we need to use B as our jump into host C.

In your linux VM, create two different terminals. In one, start a netcat listener.

$ nc -l 9999

The second terminal will be used in a moment... please switch to your Windows machine.

In your Windows system start the powercat relay:

PS: powercat -l -p 9090 -r tcp:LINUX-IP:9999

Go back to your Linux VM. In the second terminal, please type the following

$ nc WIN-IP 9090

Now what you type in this terminal will be relayed through your Windows system and should be displayed in the first linux terminal you started!

Example 8: Optional/Advanced Tasks

This section is for those who finished the labs before the other students, or the students who didn't get enough powercat fun in the limited time we have in class.

Optional Question #1

There are 65,535 ports in TCP/UDP networking. However, what happens if you specify a port that's over that? Try entering this yourself

On the Windows machine in one PowerShell prompt type the following

PS: powercat -l -p 75000

Powercat allows this!! PowerShell allows this. What is going on here?

Open up another PowerShell instance and run the import-module traick again. Type the following to try to connect to the listener you just started.

PS: powercat -c localhost -p 75000

That port does not exist, yet it doesn't throw an error!! But the client connect attempt won't work?!? What is going on?!? Get to the bottom of this mysterious port! There's several ways to solve this. We have given you some hints you can use to solve this. Use a ROT13 decoder to decipher the hints. (for instance rot13.com can help you greatly)

Hint 1:

Hfr n gbby gung pna gryy lbh jung cbegf ner va hfr

Hint 2:

Jverfunex be argpng pna gryy lbh jung cbegf ner va hfr

Hint 3:

argpng -anbo

Optional Question #2

See what methods could be used to get around execution restriction policies. Hint : there are at least 15 techniques available to bypass execution restriction policies.

Optional Question #3

We ran powercat in an administrative PowerShell prompt. Does powercat require admin access to run?

Example 9: Cleanup

Change your execution restriction policy to what it was before you started this lab. (Check what you wrote a few examples back)

PS: Set-ExecutionPolicy [What it was]

You can’t perform that action at this time.