Real-time collaboration for Jupyter Notebooks, Linux Terminals, LaTeX, VS Code, R IDE, and more,
all in one place.

1
# -*- coding: binary -*-
2

3
module Rex
4
  module Proto
5
    module Kerberos
6
      module Model
7
        # This class provides a representation of a Kerberos KRB-CRED
8
        # message definition.
9
        class KrbCred < Element
10
          # @!attribute pvno
11
          #   @return [Integer] The protocol version number
12
          attr_accessor :pvno
13
          # @!attribute msg_type
14
          #   @return [Integer] The type of a protocol message
15
          attr_accessor :msg_type
16
          # @!attribute tickets
17
          #   @return [Array<Rex::Proto::Kerberos::Model::Ticket>] Tickets encapsulated in this message
18
          attr_accessor :tickets
19
          # @!attribute enc_part
20
          #   @return [Rex::Proto::Kerberos::Model::EncryptedData] Encrypted KRB-CRED blob
21
          attr_accessor :enc_part
22

23
          def ==(other)
24
            pvno == other.pvno &&
25
              msg_type == other.msg_type &&
26
              tickets == other.tickets &&
27
              enc_part == other.enc_part
28
          end
29

30
          # Decodes the Rex::Proto::Kerberos::Model::KrbCred from an input
31
          #
32
          # @param input [String, OpenSSL::ASN1::ASN1Data] the input to decode from
33
          # @return [self] if decoding succeeds
34
          # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
35
          def decode(input)
36
            case input
37
            when String
38
              decode_string(input)
39
            when OpenSSL::ASN1::Sequence
40
              decode_asn1(input)
41
            else
42
              raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, 'Failed to decode KrbCred, invalid input'
43
            end
44

45
            self
46
          end
47

48
          # Rex::Proto::Kerberos::Model::KrbCred encoding isn't supported
49
          #
50
          # @raise [NotImplementedError]
51
          def encode
52
            elems = []
53
            elems << OpenSSL::ASN1::ASN1Data.new([encode_pvno], 0, :CONTEXT_SPECIFIC)
54
            elems << OpenSSL::ASN1::ASN1Data.new([encode_msg_type], 1, :CONTEXT_SPECIFIC)
55
            elems << OpenSSL::ASN1::ASN1Data.new([encode_tickets], 2, :CONTEXT_SPECIFIC)
56
            elems << OpenSSL::ASN1::ASN1Data.new([encode_enc_part], 3, :CONTEXT_SPECIFIC)
57

58
            seq = OpenSSL::ASN1::Sequence.new(elems)
59
            seq_asn1 = OpenSSL::ASN1::ASN1Data.new([seq], KRB_CRED, :APPLICATION)
60

61
            seq_asn1.to_der
62
          end
63

64
          # Loads a KrbCred from a kirbi file
65
          # @param [String] file_path the path to load the file from
66
          # @return [Rex::Proto::Kerberos::Model::KrbCred]
67
          def self.load_credential_from_file(file_path)
68
            unless File.readable?(file_path.to_s)
69
              raise ::ArgumentError, "Failed to load kirbi file '#{file_path}'"
70
            end
71

72
            decode(File.binread(file_path))
73
          end
74

75
          # Saves a KrbCred to a kirbi file
76
          # @param [String] file_path the path to save the file to
77
          # @return [Integer] The length written
78
          def save_credential_to_file(file_path)
79
            File.binwrite(file_path, encode)
80
          end
81

82
          private
83

84
          # Encodes the pvno
85
          #
86
          # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError]
87
          def encode_pvno
88
            bn = OpenSSL::BN.new(pvno.to_s)
89
            int = OpenSSL::ASN1::Integer.new(bn)
90

91
            int
92
          rescue OpenSSL::ASN1::ASN1Error
93
            raise Rex::Proto::Kerberos::Model::Error::KerberosDecodingError
94
          end
95

96
          # Encodes the msg_type field
97
          #
98
          # @return [OpenSSL::ASN1::Integer]
99
          def encode_msg_type
100
            bn = OpenSSL::BN.new(msg_type.to_s)
101
            int = OpenSSL::ASN1::Integer.new(bn)
102

103
            int
104
          end
105

106
          # Encodes the ticket field
107
          #
108
          # @return [OpenSSL::ASN1::Sequence]
109
          def encode_tickets
110
            encoded = tickets.map(&:encode)
111
            seq = OpenSSL::ASN1::Sequence.new(encoded)
112
          end
113

114
          # Encodes the enc_part field
115
          #
116
          # @return [String]
117
          def encode_enc_part
118
            encoded = enc_part.encode
119
          end
120

121
          # Decodes a Rex::Proto::Kerberos::Model::KrbCred
122
          #
123
          # @param input [String] the input to decode from
124
          def decode_string(input)
125
            asn1 = OpenSSL::ASN1.decode(input)
126

127
            decode_asn1(asn1)
128
          end
129

130
          # Decodes a Rex::Proto::Kerberos::Model::KrbCred from an
131
          # OpenSSL::ASN1Data
132
          #
133
          # @param input [OpenSSL::ASN1Data] the input to decode from
134
          def decode_asn1(input)
135
            input.value[0].value.each do |val|
136
              case val.tag
137
              when 0
138
                self.pvno = decode_pvno(val)
139
              when 1
140
                self.msg_type = decode_msg_type(val)
141
              when 2
142
                self.tickets = decode_tickets(val)
143
              when 3
144
                self.enc_part = decode_enc_part(val)
145
              else
146
                raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, "Failed to decode KrbCred (#{val.tag})"
147
              end
148
            end
149
          end
150

151
          # Decodes the pvno from an OpenSSL::ASN1::ASN1Data
152
          #
153
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
154
          # @return [Integer]
155
          def decode_pvno(input)
156
            input.value[0].value.to_i
157
          end
158

159
          # Decodes the msg_type from an OpenSSL::ASN1::ASN1Data
160
          #
161
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
162
          # @return [Integer]
163
          def decode_msg_type(input)
164
            input.value[0].value.to_i
165
          end
166

167
          # Decodes the tickets from an OpenSSL::ASN1::Sequence
168
          #
169
          # @param input [OpenSSL::ASN1::Sequence] the input to decode from
170
          # @return [Array<Rex::Proto::Kerberos::Model::Tickets>]
171
          def decode_tickets(input)
172
            tickets = []
173
            input.value[0].value.each do |val|
174
              tickets << Rex::Proto::Kerberos::Model::Ticket.decode(val)
175
            end
176
            tickets
177
          end
178

179
          # Decodes the enc_part
180
          #
181
          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
182
          # @return [Rex::Proto::Kerberos::Model::EncryptedData]
183
          def decode_enc_part(input)
184
            Rex::Proto::Kerberos::Model::EncryptedData.decode(input.value[0])
185
          end
186
        end
187
      end
188
    end
189
  end
190
end
191

192