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

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


15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
 
# File 'lib/msf/core/exploit/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 


51
52
53
 
# File 'lib/msf/core/exploit/smb/server.rb', line 51

def on_client_close(client)
  smb_stop(client)
end

#on_client_connect(client) ⇒ Object 


40
41
42
43
 
# File 'lib/msf/core/exploit/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 


45
46
47
48
49
 
# File 'lib/msf/core/exploit/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 


35
36
37
38
 
# File 'lib/msf/core/exploit/smb/server.rb', line 35

def setup
  super
  @state = {}
end

#smb_cmd_dispatch(cmd, c, buff) ⇒ Object 


169
170
171
172
 
# File 'lib/msf/core/exploit/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 


55
56
57
58
 
# File 'lib/msf/core/exploit/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 


182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
 
# File 'lib/msf/core/exploit/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


207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
 
# File 'lib/msf/core/exploit/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 


74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
 
# File 'lib/msf/core/exploit/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 


174
175
176
177
178
179
180
 
# File 'lib/msf/core/exploit/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 


60
61
62
63
64
65
66
67
68
69
70
71
72
 
# File 'lib/msf/core/exploit/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