How can I pass a parameter from BAT-file to an encoded powershell-script

Question

I would like to execute an encoded powershell-script from a Windows-batch and pass a parameter to it.

Let's take for example the following script:

param (
    $foo
)
Write-Host("Hello World!" + $foo)

When encoding it to base64, the result is:

cABhAHIAYQBtACAAKAANAAoAIAAgACAAIAAkAGYAbwBvAA0ACgApAA0ACgBXAHIAaQB0AGUALQBIAG8AcwB0ACgAIgBIAGUAbABsAG8AIABXAG8AcgBsAGQAIQAiACAAKwAgACQAZgBvAG8AKQA=

I do then create a batch-skript:

@ECHO OFF
powershell.exe -EncodedCommand "cABhAHIAYQBtACAAKAANAAoAIAAgACAAIAAkAGYAbwBvAA0ACgApAA0ACgBXAHIAaQB0AGUALQBIAG8AcwB0ACgAIgBIAGUAbABsAG8AIABXAG8AcgBsAGQAIQAiACAAKwAgACQAZgBvAG8AKQA="

How can I pass a parameter to the powershell to make it output a value for $foo after "Hello World!"?

Due to the circumstances, I cannot create another script-file or anything similar. The whole process should be contained in the BAT-file.

Answer 1

Powershell does not support passing arguments to a script that is encrypted natively.

You can however set variables in the .bat file, then in your script retrieve them.

For example:

$command = 'write-host $env:test '
$bytes = [System.Text.Encoding]::Unicode.GetBytes($command)
$encodedCommand = [Convert]::ToBase64String($bytes)

$encodedCommand

The encoded command is now: dwByAGkAdABlAC0AaABvAHMAdAAgACQAZQBuAHYAOgB0AGUAcwB0ACAA

In your batch file, you can now have:

@echo off
set test=MyVar
Powershell -encodedcommand dwByAGkAdABlAC0AaABvAHMAdAAgACQAZQBuAHYAOgB0AGUAcwB0ACAA

When you run the batchfile, it will now print MyVar.