Class: Rex::Proto::RFB::Client

Inherits:
Object
  • Object
show all
Includes:
Constants
Defined in:
lib/rex/proto/rfb/client.rb

Constant Summary

Constants included from Constants

Rex::Proto::RFB::Constants::DefaultPort, Rex::Proto::RFB::Constants::MajorVersions

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(sock, opts = {}) ⇒ Client

Returns a new instance of Client.



21
22
23
24
25
26
27
28
29
 
# File 'lib/rex/proto/rfb/client.rb', line 21

def initialize(sock, opts = {})
  @sock = sock
  @opts = opts

  @banner = nil
  @majver = -1
  @minver = -1
  @auth_types = []
end

Instance Attribute Details

#auth_types ⇒ Object (readonly)

Returns the value of attribute auth_types.



252
253
254
 
# File 'lib/rex/proto/rfb/client.rb', line 252

def auth_types
  @auth_types
end

#error ⇒ Object (readonly)

Returns the value of attribute error.



252
253
254
 
# File 'lib/rex/proto/rfb/client.rb', line 252

def error
  @error
end

#majver ⇒ Object (readonly)

Returns the value of attribute majver.



252
253
254
 
# File 'lib/rex/proto/rfb/client.rb', line 252

def majver
  @majver
end

#minver ⇒ Object (readonly)

Returns the value of attribute minver.



252
253
254
 
# File 'lib/rex/proto/rfb/client.rb', line 252

def minver
  @minver
end

#view_only ⇒ Object (readonly)

Returns the value of attribute view_only.



252
253
254
 
# File 'lib/rex/proto/rfb/client.rb', line 252

def view_only
  @view_only
end

Instance Method Details

#authenticate(password = nil) ⇒ Object 



92
93
94
 
# File 'lib/rex/proto/rfb/client.rb', line 92

def authenticate(password = nil)
  authenticate_with_user(nil, password)
end

#authenticate_with_type(type, username = nil, password = nil) ⇒ Object 



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
 
# File 'lib/rex/proto/rfb/client.rb', line 101

def authenticate_with_type(type, username = nil, password = nil)
  return false if !type

  # Authenticate.
  case type
  when AuthType::None
    # Nothing here.

  when AuthType::VNC
    return false if !negotiate_vnc_auth(password)

  when AuthType::ARD
    return false if !negotiate_ard_auth(username, password)

  end

  # Handle reading the security result message
  result = @sock.get_once(4)
  if !result
    @error = 'Unable to read auth result'
    return false
  end

  result = result.unpack('N').first
  case result
  when 0
    return true

  when 1
    if @minver >= 8
      msg = read_error_message
      @error = "Authentication failed: #{msg}"
    else
      @error = 'Authentication failed'
    end
  when 2
    @error = 'Too many authentication attempts'
  else
    @error = "Unknown authentication result: #{result}"
  end

  false
end

#authenticate_with_user(username = nil, password = nil) ⇒ Object 



96
97
98
99
 
# File 'lib/rex/proto/rfb/client.rb', line 96

def authenticate_with_user(username = nil, password = nil)
  type = negotiate_authentication
  authenticate_with_type(type, username, password)
end

#connect(password = nil) ⇒ Object 



76
77
78
79
80
81
82
 
# File 'lib/rex/proto/rfb/client.rb', line 76

def connect(password = nil)
  return false if !handshake
  return false if !authenticate(password)
  return false if !send_client_init

  true
end

#handshake ⇒ Object 



39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
 
# File 'lib/rex/proto/rfb/client.rb', line 39

def handshake
  @banner = @sock.get_once(12)
  if !@banner
    @error = 'Unable to obtain banner from server'
    return false
  end

  # RFB Protocol Version 3.3 (1998-01)
  # RFB Protocol Version 3.7 (2003-08)
  # RFB Protocol Version 3.8 (2007-06)

  if @banner =~ /RFB ([0-9]{3})\.([0-9]{3})/
    @majver = Regexp.last_match(1).to_i
    unless Constants::MajorVersions.include?(@majver)
      @error = "Invalid major version number: #{@majver}"
      return false
    end
  else
    @error = "Invalid RFB banner: #{@banner}"
    return false
  end

  @minver = Regexp.last_match(2).to_i

  # Forces version 3 to be used. This adds support for version 4 servers.
  # Minor version is at least 3, to work with Apple devices. Attempting to be purely dynamic
  # based on the received server version can result in a 5.0 server version response
  # setting the client version to 3.0 when it should be at least 3.3, so code checks for this.
  # TODO: Add support for Version 4.
  # Version 4 adds additional information to the packet regarding supported
  # authentication types.
  our_ver = format("RFB %03d.%03d\n", 3, @minver < 3 ? 8 : @minver)
  @sock.put(our_ver)

  true
end

#negotiate_ard_auth(username = nil, password = nil) ⇒ Object 



219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
 
# File 'lib/rex/proto/rfb/client.rb', line 219

def negotiate_ard_auth(username = nil, password = nil)
  generator = @sock.get_once(2)
  if !generator or generator.length != 2
    @error = 'Unable to obtain ARD challenge: invalid generator value'
    return false
  end
  generator = generator.unpack('n').first

  key_length = @sock.get_once(2)
  if !key_length or key_length.length != 2
    @error = 'Unable to obtain ARD challenge: invalid key length'
    return false
  end
  key_length = key_length.unpack('n').first

  prime_modulus = @sock.get_once(key_length)
  if !prime_modulus or prime_modulus.length != key_length
    @error = 'Unable to obtain ARD challenge: invalid prime modulus'
    return false
  end

  peer_public_key = @sock.get_once(key_length)
  if !peer_public_key or peer_public_key.length != key_length
    @error = 'Unable to obtain ARD challenge: invalid public key'
    return false
  end

  response = Cipher.encrypt_ard(username, password, generator, key_length, prime_modulus, peer_public_key)
  @sock.put(response)

  true
end

#negotiate_authentication ⇒ Object 



145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
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/rex/proto/rfb/client.rb', line 145

def negotiate_authentication
  # Authentication type negotiation is protocol version specific.
  if @minver < 7
    buf = @sock.get_once(4)
    if !buf
      @error = 'Unable to obtain requested authentication method'
      return nil
    end
    @auth_types = buf.unpack('N')
    if !@auth_types or @auth_types.first == 0
      msg = read_error_message
      @error = "No authentication types available: #{msg}"
      return nil
    end
  else
    buf = @sock.get_once(1)
    if !buf
      @error = 'Unable to obtain supported authentication method count'
      return nil
    end

    # first byte is number of security types
    num_types = buf.unpack('C').first
    if (num_types == 0)
      msg = read_error_message
      @error = "No authentication types available: #{msg}"
      return nil
    end

    buf = @sock.get_once(num_types)
    if !buf or buf.length != num_types
      @error = 'Unable to read authentication types'
      return nil
    end

    @auth_types = buf.unpack('C*')
  end

  if !@auth_types or @auth_types.length < 1
    @error = 'No authentication types found'
    return nil
  end

  # Select the one we prefer
  selected = nil
  selected ||= AuthType::None if @opts[:allow_none] and @auth_types.include? AuthType::None
  selected ||= AuthType::VNC if @auth_types.include? AuthType::VNC
  selected ||= AuthType::ARD if @auth_types.include? AuthType::ARD

  if !selected
    auth_strings = @auth_types.map { |i| Rex::Proto::RFB::AuthType.to_s(i) }
    @error = "No supported authentication method found. All available options: #{auth_strings.join(', ')}"
    return nil
  end

  # For 3.7 and later, clients must state which security-type to use
  @sock.put([selected].pack('C')) if @minver >= 7

  selected
end

#negotiate_vnc_auth(password = nil) ⇒ Object 



206
207
208
209
210
211
212
213
214
215
216
217
 
# File 'lib/rex/proto/rfb/client.rb', line 206

def negotiate_vnc_auth(password = nil)
  challenge = @sock.get_once(16)
  if !challenge or challenge.length != 16
    @error = 'Unable to obtain VNC challenge'
    return false
  end

  response = Cipher.encrypt(challenge, password)
  @sock.put(response)

  true
end

#read_error_message ⇒ Object 



31
32
33
34
35
36
37
 
# File 'lib/rex/proto/rfb/client.rb', line 31

def read_error_message
  len = @sock.get_once(4)
  return 'Unknown error' if !len or len.length != 4

  len = len.unpack('N').first
  @sock.get_once(len)
end

#send_client_init ⇒ Object 



84
85
86
87
88
89
90
 
# File 'lib/rex/proto/rfb/client.rb', line 84

def send_client_init
  if @opts[:exclusive]
    @sock.put("\x00") # do share.
  else
    @sock.put("\x01") # do share.
  end
end