Add shutdown method to Exploit::Remote::Tcp

[bcoles]

This PR exposes a shutdown method for Exploit::Remote::Tcp.sock.

I encountered a protocol recently which required sending sock.shutdown(1) before replying. The server refused to return data until it received a promise that no more data was to be sent.

• https://www.rubydoc.info/stdlib/socket/BasicSocket:shutdown
• https://perldoc.perl.org/functions/shutdown.html

[busterb]

Would it be alright to prefer one of the symbolic representations instead, as mentioned in the ruby docs? :SHUT_WR instead of 1 ?

[bcoles]

Would it be alright to prefer one of the symbolic representations instead, as mentioned in the ruby docs? :SHUT_WR instead of 1 ?

Yeah, they're interchangeable. Updated.

[wvu]

[1] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> connect
=> #<Socket:fd 19>
[2] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> disconnect
=> #<Socket:(closed)>
[3] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> connect
=> #<Socket:fd 19>
[4] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> shutdown
=> true
[5] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> sock
=> #<Socket:fd 19>
[6] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> sock.close
=> nil
[7] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)> sock
=> #<Socket:(closed)>
[8] pry(#<Msf::Modules::Exploit__Bsd__Finger__Morris_fingerd_bof::MetasploitModule>)>

    1   0.000000    127.0.0.1 → 127.0.0.1    51153 79 TCP 68 51153 → 79 [SYN] Seq=0 Win=65535 Len=0 MSS=16344 WS=64 TSval=2564325313 TSecr=0 SACK_PERM=1
    2   0.000056    127.0.0.1 → 127.0.0.1    79 51153 TCP 68 79 → 51153 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=16344 WS=64 TSval=2564325313 TSecr=2564325313 SACK_PERM=1
    3   0.000065    127.0.0.1 → 127.0.0.1    51153 79 TCP 56 51153 → 79 [ACK] Seq=1 Ack=1 Win=408256 Len=0 TSval=2564325313 TSecr=2564325313
    4   0.000076    127.0.0.1 → 127.0.0.1    79 51153 TCP 56 [TCP Window Update] 79 → 51153 [ACK] Seq=1 Ack=1 Win=408256 Len=0 TSval=2564325313 TSecr=2564325313
    5   7.131531    127.0.0.1 → 127.0.0.1    51153 79 TCP 56 51153 → 79 [FIN, ACK] Seq=1 Ack=1 Win=408256 Len=0 TSval=2564332412 TSecr=2564325313
    6   7.131560    127.0.0.1 → 127.0.0.1    79 51153 TCP 56 79 → 51153 [ACK] Seq=1 Ack=2 Win=408256 Len=0 TSval=2564332412 TSecr=2564332412
    7   7.131611    127.0.0.1 → 127.0.0.1    79 51153 TCP 56 79 → 51153 [FIN, ACK] Seq=1 Ack=2 Win=408256 Len=0 TSval=2564332412 TSecr=2564332412
    8   7.131633    127.0.0.1 → 127.0.0.1    51153 79 TCP 56 51153 → 79 [ACK] Seq=2 Ack=2 Win=408256 Len=0 TSval=2564332412 TSecr=2564332412
    9   8.490880    127.0.0.1 → 127.0.0.1    51154 79 TCP 68 51154 → 79 [SYN] Seq=0 Win=65535 Len=0 MSS=16344 WS=64 TSval=2564333763 TSecr=0 SACK_PERM=1
   10   8.490939    127.0.0.1 → 127.0.0.1    79 51154 TCP 68 79 → 51154 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=16344 WS=64 TSval=2564333763 TSecr=2564333763 SACK_PERM=1
   11   8.490948    127.0.0.1 → 127.0.0.1    51154 79 TCP 56 51154 → 79 [ACK] Seq=1 Ack=1 Win=408256 Len=0 TSval=2564333763 TSecr=2564333763
   12   8.490957    127.0.0.1 → 127.0.0.1    79 51154 TCP 56 [TCP Window Update] 79 → 51154 [ACK] Seq=1 Ack=1 Win=408256 Len=0 TSval=2564333763 TSecr=2564333763
   13  10.527828    127.0.0.1 → 127.0.0.1    51154 79 TCP 56 51154 → 79 [FIN, ACK] Seq=1 Ack=1 Win=408256 Len=0 TSval=2564335784 TSecr=2564333763
   14  10.527887    127.0.0.1 → 127.0.0.1    79 51154 TCP 56 79 → 51154 [ACK] Seq=1 Ack=2 Win=408256 Len=0 TSval=2564335784 TSecr=2564335784
   15  10.527914    127.0.0.1 → 127.0.0.1    79 51154 TCP 56 79 → 51154 [FIN, ACK] Seq=1 Ack=2 Win=408256 Len=0 TSval=2564335784 TSecr=2564335784
   16  10.527938    127.0.0.1 → 127.0.0.1    51154 79 TCP 56 51154 → 79 [ACK] Seq=2 Ack=2 Win=408256 Len=0 TSval=2564335784 TSecr=2564335784

[wvu]

Release Notes

The shutdown method has been added to the Msf::Exploit::Remote::Tcp mixin. It exposes the shutdown method from Rex::Socket::Tcp to provide a consistent interface for module developers. Please note that the disconnect method will shut down and close a socket, which isn't always desired.