Module: Msf::Exploit::Remote::SMB::Server

Includes:
NTLM, TcpServer
Included in:
Share
Defined in:
lib/msf/core/exploit/remote/smb/server.rb,
lib/msf/core/exploit/remote/smb/server/share.rb,
lib/msf/core/exploit/remote/smb/server/share/command.rb,
lib/msf/core/exploit/remote/smb/server/share/command/close.rb,
lib/msf/core/exploit/remote/smb/server/share/command/trans2.rb,
lib/msf/core/exploit/remote/smb/server/share/command/negotiate.rb,
lib/msf/core/exploit/remote/smb/server/share/command/read_andx.rb,
lib/msf/core/exploit/remote/smb/server/share/information_level.rb,
lib/msf/core/exploit/remote/smb/server/share/command/nt_create_andx.rb,
lib/msf/core/exploit/remote/smb/server/share/information_level/find.rb,
lib/msf/core/exploit/remote/smb/server/share/information_level/query.rb,
lib/msf/core/exploit/remote/smb/server/share/command/session_setup_andx.rb,
lib/msf/core/exploit/remote/smb/server/share/command/trans2/find_first2.rb,
lib/msf/core/exploit/remote/smb/server/share/command/trans2/query_file_information.rb,
lib/msf/core/exploit/remote/smb/server/share/command/trans2/query_path_information.rb

Overview

This mixin provides a minimal SMB server

Defined Under Namespace

Modules: Share

Constant Summary collapse

CONST = 
::Rex::Proto::SMB::Constants
CRYPT = 
::Rex::Proto::SMB::Crypt
UTILS = 
::Rex::Proto::SMB::Utils
XCEPT = 
::Rex::Proto::SMB::Exceptions
EVADE = 
::Rex::Proto::SMB::Evasions

Instance Attribute Summary

Attributes included from Msf::Exploit::Remote::SocketServer

#service

Instance Method Summary collapse

Methods included from TcpServer

#ssl, #ssl_cert, #ssl_cipher, #ssl_compression, #start_service

Methods included from Msf::Exploit::Remote::SocketServer

#_determine_server_comm, #cleanup, #exploit, #primer, #regenerate_payload, #srvhost, #srvport, #start_service, #stop_service, #via_string_for_ip

Instance Method Details

#initialize(info = {}) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 15

def initialize(info = {})
  super

  deregister_options('SSL', 'SSLCert')
  register_options(
    [
      OptPort.new('SRVPORT', [ true, 'The local port to listen on.', 445 ])
    ], self.class)

  register_advanced_options(
    [
      OptInt.new('SMBServerMaximumBuffer', [ true, 'The maximum number of data in megabytes to buffer', 2 ]),
      OptInt.new('SMBServerIdleTimeout', [ true, 'The maximum amount of time to keep an idle session open in seconds', 120 ])
    ], self.class)

  @smb_server_last_pool_sweep = Time.now.to_f
  @smb_server_pool_mutex = Mutex.new
  @smb_server_request_counter = 0
end

#on_client_close(client) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 51

def on_client_close(client)
  smb_stop(client)
end

#on_client_connect(client) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 40

def on_client_connect(client)
  # print_status("New SMB connection from #{client.peerhost}:#{client.peerport}")
  smb_conn(client)
end

#on_client_data(client) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 45

def on_client_data(client)
  # print_status("New data from #{client.peerhost}:#{client.peerport}")
  smb_recv(client)
  true
end

#setup ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 35

def setup
  super
  @state = {}
end

#smb_cmd_dispatch(cmd, c, buff) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 169

def smb_cmd_dispatch(cmd, c, buff)
  smb = @state[c]
  print_status("Received command #{cmd} from #{smb[:name]}")
end

#smb_conn(c) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 55

def smb_conn(c)
  @state[c] = {:name => "#{c.peerhost}:#{c.peerport}", :ip => c.peerhost, :port => c.peerport}
  smb_pool_update(c)
end

#smb_error(cmd, c, errorclass, esn = false) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 182

def smb_error(cmd, c, errorclass, esn = false)
  # 0xc0000022 = Deny
  # 0xc000006D = Logon_Failure
  # 0x00000000 = Ignore
  pkt = CONST::SMB_BASE_PKT.make_struct
  smb_set_defaults(c, pkt)
  pkt['Payload']['SMB'].v['Command'] = cmd
  pkt['Payload']['SMB'].v['Flags1']  = CONST::FLAGS_REQ_RES | CONST::FLAGS_CASE_SENSITIVE
  if esn
    pkt['Payload']['SMB'].v['Flags2']  =
      CONST::FLAGS2_UNICODE_STRINGS +
      CONST::FLAGS2_EXTENDED_SECURITY +
      CONST::FLAGS2_32_BIT_ERROR_CODES +
      CONST::FLAGS2_LONG_PATH_COMPONENTS
  else
    pkt['Payload']['SMB'].v['Flags2']  =
      CONST::FLAGS2_UNICODE_STRINGS +
      CONST::FLAGS2_32_BIT_ERROR_CODES +
      CONST::FLAGS2_LONG_PATH_COMPONENTS
  end
  pkt['Payload']['SMB'].v['ErrorClass'] = errorclass
  c.put(pkt.to_s)
end

#smb_pool_update(c) ⇒ Object

Update the last-seen timestamp and purge old entries


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 207

def smb_pool_update(c)

  @state[c][:last_action] = Time.now.to_f
  @smb_server_request_counter += 1

  unless @smb_server_request_counter % 100 == 0 ||
    @smb_server_last_pool_sweep + datastore['SMBServerIdleTimeout'].to_f < Time.now.to_f
    return
  end

  # Synchronize pool sweeps in case we move to threaded services
  @smb_server_pool_mutex.synchronize do
    purge_list = []

    @smb_server_last_pool_sweep = Time.now.to_f

    @state.keys.each do |sc|
      if @state[sc][:last_action] + datastore['SMBServerIdleTimeout'].to_f < Time.now.to_f
        purge_list << sc
      end
    end

    # Purge any idle connections to rescue file descriptors
    purge_list.each do |sc|
      vprint_status("Dropping connection from #{@state[sc][:name]} due to idle timeout...")
      smb_stop(sc)
    end
  end
end

#smb_recv(c) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 74

def smb_recv(c)
  smb = @state[c]
  smb[:data] ||= ''

  buff = ''
  begin
    buff = c.get_once(-1, 0.25)
      # Handle any number of errors that a read can trigger depending on socket state
  rescue ::IOError, ::EOFError,
    ::Errno::ECONNRESET, ::Errno::ENOTCONN, ::Errno::ECONNABORTED,
    ::Errno::ETIMEDOUT, ::Errno::ENETRESET, ::Errno::ESHUTDOWN
    vprint_status("Dropping connection from #{smb[:name]} due to exception: #{$!.class} #{$!}")
    smb_stop(c)
    return
  end

  # The client said it had data, but lied, kill the session
  unless buff and buff.length > 0
    vprint_status("Dropping connection from #{smb[:name]} due to empty payload...")
    smb_stop(c)
    return
  end

  # Append the new data to the buffer
  smb[:data] << buff

  # Prevent a simplistic DoS if the buffer is too big
  if smb[:data].length > (1024*1024*datastore['SMBServerMaximumBuffer'])
    vprint_status("Dropping connection from #{smb[:name]} due to oversized buffer of #{smb[:data].length} bytes...")
    smb_stop(c)
    return
  end

  # Update the last-seen timestamp and purge old entries
  smb_pool_update(c)

  while(smb[:data].length > 0)

    return if smb[:data].length < 4

    plen = smb[:data][2,2].unpack('n')[0]

    return if smb[:data].length < plen+4

    buff = smb[:data].slice!(0, plen+4)

    pkt_nbs = CONST::NBRAW_PKT.make_struct
    pkt_nbs.from_s(buff)

    # print_status("NetBIOS request from #{smb[:name]} #{pkt_nbs.v['Type']} #{pkt_nbs.v['Flags']} #{buff.inspect}")

    # Check for a NetBIOS name request
    if (pkt_nbs.v['Type'] == 0x81)
      # Accept any name they happen to send

      host_dst = UTILS.nbname_decode(pkt_nbs.v['Payload'][1,32]).gsub(/[\x00\x20]+$/n, '')
      host_src = UTILS.nbname_decode(pkt_nbs.v['Payload'][35,32]).gsub(/[\x00\x20]+$/n, '')

      smb[:nbdst] = host_dst
      smb[:nbsrc] = host_src

      # print_status("NetBIOS session request from #{smb[:name]} (asking for #{host_dst} from #{host_src})")
      c.write("\x82\x00\x00\x00")
      next
    end


    #
    # TODO: Support AndX parameters
    #


    # Cast this to a generic SMB structure
    pkt = CONST::SMB_BASE_PKT.make_struct
    pkt.from_s(buff)

    # Only respond to requests, ignore server replies
    if (pkt['Payload']['SMB'].v['Flags1'] & 128 != 0)
      vprint_status("Dropping connection from #{smb[:name]} due to missing client request flag")
      smb_stop(c)
      return
    end

    cmd = pkt['Payload']['SMB'].v['Command']
    begin
      smb_cmd_dispatch(cmd, c, buff)
    rescue ::Interrupt
      raise $!
    rescue ::Exception => e
      print_status("Error processing request from #{smb[:name]} (#{cmd}): #{e.class} #{e} #{e.backtrace}")
      next
    end
  end
end

#smb_set_defaults(c, pkt) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 174

def smb_set_defaults(c, pkt)
  smb = @state[c]
  pkt['Payload']['SMB'].v['ProcessID'] = smb[:process_id].to_i
  pkt['Payload']['SMB'].v['UserID'] = smb[:user_id].to_i
  pkt['Payload']['SMB'].v['TreeID'] = smb[:tree_id].to_i
  pkt['Payload']['SMB'].v['MultiplexID'] = smb[:multiplex_id].to_i
end

#smb_stop(c) ⇒ Object 


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# File 'lib/msf/core/exploit/remote/smb/server.rb', line 60

def smb_stop(c)
  # Make sure the socket is closed
  begin
    c.close
      # Handle any number of errors that a double-close or failed shutdown can trigger
  rescue ::IOError, ::EOFError,
    ::Errno::ECONNRESET, ::Errno::ENOTCONN, ::Errno::ECONNABORTED,
    ::Errno::ETIMEDOUT, ::Errno::ENETRESET, ::Errno::ESHUTDOWN
  end

  # Delete the state table entry
  @state.delete(c)
end