Class: Rex::Post::Meterpreter::Client

Inherits:
Object
  • Object
show all
Includes:
ChannelContainer, PacketDispatcher
Defined in:
lib/rex/post/meterpreter/client.rb

Overview

This class represents a logical meterpreter client class. This class provides an interface that is compatible with the Rex post-exploitation interface in terms of the feature set that it attempts to expose. This class is meant to drive a single meterpreter client session.

Constant Summary collapse

@@ext_hash =

Extension name to class hash.

{}
@@ssl_cached_cert =

Cached auto-generated SSL certificate

nil
@@ssl_mutex =

Mutex to synchronize class-wide operations

::Mutex.new

Constants included from PacketDispatcher

PacketDispatcher::PACKET_TIMEOUT, PacketDispatcher::PING_TIME

Instance Attribute Summary collapse

Attributes included from ChannelContainer

#channels

Attributes included from PacketDispatcher

#comm_mutex, #passive_service, #recv_queue, #send_queue

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ChannelContainer

#add_channel, #find_channel, #initialize_channels, #remove_channel

Methods included from PacketDispatcher

#add_response_waiter, #deregister_inbound_handler, #dispatch_inbound_packet, #initialize_inbound_handlers, #initialize_passive_dispatcher, #keepalive, #monitor_socket, #monitor_stop, #notify_response_waiter, #on_passive_request, #receive_packet, #register_inbound_handler, #remove_response_waiter, #send_packet, #send_packet_wait_response, #send_request, #shutdown_passive_dispatcher

Constructor Details

#initialize(sock, opts = {}) ⇒ Client

Initializes the client context with the supplied socket through which communication with the server will be performed.



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# File 'lib/rex/post/meterpreter/client.rb', line 80

def initialize(sock,opts={})
  init_meterpreter(sock, opts)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(symbol, *args) ⇒ Object

Translates unhandled methods into registered extension aliases if a matching extension alias exists for the supplied symbol.



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# File 'lib/rex/post/meterpreter/client.rb', line 289

def method_missing(symbol, *args)
  #$stdout.puts("method_missing: #{symbol}")
  self.ext_aliases.aliases[symbol.to_s]
end

Instance Attribute Details

#alive ⇒ Object

Whether this session is alive. If the socket is disconnected or broken, this will be false



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# File 'lib/rex/post/meterpreter/client.rb', line 432

def alive
  @alive
end

#capabilities ⇒ Object

The libraries available to this meterpreter server



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# File 'lib/rex/post/meterpreter/client.rb', line 440

def capabilities
  @capabilities
end

#comm_timeout ⇒ Object

The Communication Timeout



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# File 'lib/rex/post/meterpreter/client.rb', line 464

def comm_timeout
  @comm_timeout
end

#commands ⇒ Object

A list of the commands



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# File 'lib/rex/post/meterpreter/client.rb', line 484

def commands
  @commands
end

#conn_id ⇒ Object

The Connection ID



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# File 'lib/rex/post/meterpreter/client.rb', line 444

def conn_id
  @conn_id
end

#encode_unicode ⇒ Object

Flag indicating whether to hex-encode UTF-8 file names and other strings



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# File 'lib/rex/post/meterpreter/client.rb', line 480

def encode_unicode
  @encode_unicode
end

#expiration ⇒ Object

The Session Expiration Timeout



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# File 'lib/rex/post/meterpreter/client.rb', line 460

def expiration
  @expiration
end

#ext ⇒ Object

The extension alias under which all extensions can be accessed by name. For example:

client.ext.stdapi



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# File 'lib/rex/post/meterpreter/client.rb', line 415

def ext
  @ext
end

#last_checkin ⇒ Object

The timestamp of the last received response



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# File 'lib/rex/post/meterpreter/client.rb', line 488

def last_checkin
  @last_checkin
end

#passive_dispatcher ⇒ Object

The Passive Dispatcher



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# File 'lib/rex/post/meterpreter/client.rb', line 476

def passive_dispatcher
  @passive_dispatcher
end

#response_timeout ⇒ Object

The timeout value to use when waiting for responses.



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# File 'lib/rex/post/meterpreter/client.rb', line 423

def response_timeout
  @response_timeout
end

#retry_total ⇒ Object

The total time for retrying connections



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# File 'lib/rex/post/meterpreter/client.rb', line 468

def retry_total
  @retry_total
end

#retry_wait ⇒ Object

The time to wait between retry attempts



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# File 'lib/rex/post/meterpreter/client.rb', line 472

def retry_wait
  @retry_wait
end

#send_keepalives ⇒ Object

Whether to send pings every so often to determine liveness.



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# File 'lib/rex/post/meterpreter/client.rb', line 427

def send_keepalives
  @send_keepalives
end

#sock ⇒ Object

The socket the client is communicating over.



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# File 'lib/rex/post/meterpreter/client.rb', line 419

def sock
  @sock
end

#ssl ⇒ Object

Use SSL (HTTPS)



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# File 'lib/rex/post/meterpreter/client.rb', line 452

def ssl
  @ssl
end

#ssl_cert ⇒ Object

Use this SSL Certificate (unified PEM)



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# File 'lib/rex/post/meterpreter/client.rb', line 456

def ssl_cert
  @ssl_cert
end

#target_id ⇒ Object

The unique target identifier for this payload



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# File 'lib/rex/post/meterpreter/client.rb', line 436

def target_id
  @target_id
end

#url ⇒ Object

The Connect URL



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# File 'lib/rex/post/meterpreter/client.rb', line 448

def url
  @url
end

Class Method Details

.check_ext_hash(name) ⇒ Object

Checks the extension hash to see if a class has already been associated with the supplied extension name.



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# File 'lib/rex/post/meterpreter/client.rb', line 65

def self.check_ext_hash(name)
  @@ext_hash[name]
end

.default_timeout ⇒ Object

Returns the default timeout that request packets will use when waiting for a response.



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# File 'lib/rex/post/meterpreter/client.rb', line 275

def Client.default_timeout
  return 300
end

.lookup_error(code) ⇒ Object

Lookup the error that occurred



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# File 'lib/rex/post/meterpreter/client.rb', line 57

def self.lookup_error(code)
  code
end

.set_ext_hash(name, klass) ⇒ Object

Stores the name to class association for the supplied extension name.



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# File 'lib/rex/post/meterpreter/client.rb', line 72

def self.set_ext_hash(name, klass)
  @@ext_hash[name] = klass
end

Instance Method Details

#add_extension(name, commands = []) ⇒ Object

Loads the client half of the supplied extension and initializes it as a registered extension that can be reached through client.ext..



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# File 'lib/rex/post/meterpreter/client.rb', line 304

def add_extension(name, commands=[])
  self.commands |= commands

  # Check to see if this extension has already been loaded.
  if ((klass = self.class.check_ext_hash(name.downcase)) == nil)
    old = Rex::Post::Meterpreter::Extensions.constants
    require("rex/post/meterpreter/extensions/#{name.downcase}/#{name.downcase}")
    new = Rex::Post::Meterpreter::Extensions.constants

    # No new constants added?
    if ((diff = new - old).empty?)
      diff = [ name.capitalize ]
    end

    klass = Rex::Post::Meterpreter::Extensions.const_get(diff[0]).const_get(diff[0])

    # Save the module name to class association now that the code is
    # loaded.
    self.class.set_ext_hash(name.downcase, klass)
  end

  # Create a new instance of the extension
  inst = klass.new(self)

  self.ext.aliases[inst.name] = inst

  return true
end

#cleanup_meterpreter ⇒ Object

Cleans up the meterpreter instance, terminating the dispatcher thread.



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# File 'lib/rex/post/meterpreter/client.rb', line 87

def cleanup_meterpreter
  if not self.skip_cleanup
    ext.aliases.each_value do | extension |
      extension.cleanup if extension.respond_to?( 'cleanup' )
    end
  end

  dispatcher_thread.kill if dispatcher_thread

  if not self.skip_cleanup
    core.shutdown rescue nil
  end

  shutdown_passive_dispatcher
end

#deregister_extension(name) ⇒ Object

Deregisters an extension alias of the supplied name.



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# File 'lib/rex/post/meterpreter/client.rb', line 336

def deregister_extension(name)
  self.ext.aliases.delete(name)
end

#deregister_extension_alias(name) ⇒ Object

Deregisters a previously registered extension alias.



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# File 'lib/rex/post/meterpreter/client.rb', line 379

def deregister_extension_alias(name)
  self.ext_aliases.aliases.delete(name)
end

#dump_extension_tree ⇒ Object

Dumps the extension tree.



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# File 'lib/rex/post/meterpreter/client.rb', line 386

def dump_extension_tree()
  items = []
  items.concat(self.ext.dump_alias_tree('client.ext'))
  items.concat(self.ext_aliases.dump_alias_tree('client'))

  return items.sort
end

#each_extension(&block) ⇒ Object

Enumerates all of the loaded extensions.



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# File 'lib/rex/post/meterpreter/client.rb', line 343

def each_extension(&block)
  self.ext.aliases.each(block)
end

#generate_ssl_context ⇒ Object 



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# File 'lib/rex/post/meterpreter/client.rb', line 225

def generate_ssl_context

  ctx = nil
  ssl_cert_info = nil

  loop do

    # Load a custom SSL certificate if one has been specified
    if self.ssl_cert
      wlog("Loading custom SSL certificate for Meterpreter session")
      ssl_cert_info = Rex::Socket::SslTcpServer.ssl_parse_pem(self.ssl_cert)
      wlog("Loaded custom SSL certificate for Meterpreter session")
      break
    end

    # Generate a certificate if necessary and cache it
    if ! @@ssl_cached_cert
      @@ssl_mutex.synchronize do
        wlog("Generating SSL certificate for Meterpreter sessions")
        @@ssl_cached_cert = Rex::Socket::SslTcpServer.ssl_generate_certificate
        wlog("Generated SSL certificate for Meterpreter sessions")
      end
    end

    # Use the cached certificate
    ssl_cert_info = @@ssl_cached_cert
    break
  end

  # Create a new context for each session
  ctx = OpenSSL::SSL::SSLContext.new()
  ctx.key = ssl_cert_info[0]
  ctx.cert = ssl_cert_info[1]
  ctx.extra_chain_cert = ssl_cert_info[2]
  ctx.options = 0
  ctx.session_id_context = Rex::Text.rand_text(16)

  ctx
end

#init_meterpreter(sock, opts = {}) ⇒ Object

Initializes the meterpreter client instance



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# File 'lib/rex/post/meterpreter/client.rb', line 106

def init_meterpreter(sock,opts={})
  self.sock         = sock
  self.parser       = PacketParser.new
  self.ext          = ObjectAliases.new
  self.ext_aliases  = ObjectAliases.new
  self.alive        = true
  self.target_id    = opts[:target_id]
  self.capabilities = opts[:capabilities] || {}
  self.commands     = []
  self.last_checkin = Time.now

  self.conn_id      = opts[:conn_id]
  self.url          = opts[:url]
  self.ssl          = opts[:ssl]
  self.expiration   = opts[:expiration]
  self.comm_timeout = opts[:comm_timeout]
  self.retry_total  = opts[:retry_total]
  self.retry_wait   = opts[:retry_wait]
  self.passive_dispatcher = opts[:passive_dispatcher]

  self.response_timeout = opts[:timeout] || self.class.default_timeout
  self.send_keepalives  = true

  # TODO: Clarify why we don't allow unicode to be set in initial options
  # self.encode_unicode   = opts.has_key?(:encode_unicode) ? opts[:encode_unicode] : true
  self.encode_unicode = false

  # The SSL certificate is being passed down as a file path
  if opts[:ssl_cert]
    if ! ::File.exists? opts[:ssl_cert]
      elog("SSL certificate at #{opts[:ssl_cert]} does not exist and will be ignored")
    else
      # Load the certificate the same way that SslTcpServer does it
      self.ssl_cert = ::File.read(opts[:ssl_cert])
    end
  end

  if opts[:passive_dispatcher]
    initialize_passive_dispatcher

    register_extension_alias('core', ClientCore.new(self))

    initialize_inbound_handlers
    initialize_channels

    # Register the channel inbound packet handler
    register_inbound_handler(Rex::Post::Meterpreter::Channel)
  else
    # Switch the socket to SSL mode and receive the hello if needed
    if capabilities[:ssl] and not opts[:skip_ssl]
      swap_sock_plain_to_ssl()
    end

    register_extension_alias('core', ClientCore.new(self))

    initialize_inbound_handlers
    initialize_channels

    # Register the channel inbound packet handler
    register_inbound_handler(Rex::Post::Meterpreter::Channel)

    monitor_socket
  end
end

#register_extension_alias(name, ext) ⇒ Object

Registers an aliased extension that can be referenced through client.name.



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# File 'lib/rex/post/meterpreter/client.rb', line 351

def register_extension_alias(name, ext)
  self.ext_aliases.aliases[name] = ext
  # Whee!  Syntactic sugar, where art thou?
  #
  # Create an instance method on this object called +name+ that returns
  # +ext+.  We have to do it this way instead of simply
  # self.class.class_eval so that other meterpreter sessions don't get
  # extension methods when this one does
  (class << self; self; end).class_eval do
    define_method(name.to_sym) do
      ext
    end
  end
  ext
end

#register_extension_aliases(aliases) ⇒ Object

Registers zero or more aliases that are provided in an array.



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# File 'lib/rex/post/meterpreter/client.rb', line 370

def register_extension_aliases(aliases)
  aliases.each { |a|
    register_extension_alias(a['name'], a['ext'])
  }
end

#swap_sock_plain_to_ssl ⇒ Object 



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# File 'lib/rex/post/meterpreter/client.rb', line 171

def swap_sock_plain_to_ssl
  # Create a new SSL session on the existing socket
  ctx = generate_ssl_context()
  ssl = OpenSSL::SSL::SSLSocket.new(sock, ctx)

  # Use non-blocking OpenSSL operations on Windows
  if !( ssl.respond_to?(:accept_nonblock) and Rex::Compat.is_windows )
    ssl.accept
  else
    begin
      ssl.accept_nonblock

    # Ruby 1.8.7 and 1.9.0/1.9.1 uses a standard Errno
    rescue ::Errno::EAGAIN, ::Errno::EWOULDBLOCK
        IO::select(nil, nil, nil, 0.10)
        retry

    # Ruby 1.9.2+ uses IO::WaitReadable/IO::WaitWritable
    rescue ::Exception => e
      if ::IO.const_defined?('WaitReadable') and e.kind_of?(::IO::WaitReadable)
        IO::select( [ ssl ], nil, nil, 0.10 )
        retry
      end

      if ::IO.const_defined?('WaitWritable') and e.kind_of?(::IO::WaitWritable)
        IO::select( nil, [ ssl ], nil, 0.10 )
        retry
      end

      raise e
    end
  end

  self.sock.extend(Rex::Socket::SslTcp)
  self.sock.sslsock = ssl
  self.sock.sslctx  = ctx
  self.sock.sslhash = Rex::Text.sha1_raw(ctx.cert.to_der)

  tag = self.sock.get_once(-1, 30)
  if(not tag or tag !~ /^GET \//)
    raise RuntimeError, "Could not read the HTTP hello token"
  end
end

#swap_sock_ssl_to_plain ⇒ Object 



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# File 'lib/rex/post/meterpreter/client.rb', line 215

def swap_sock_ssl_to_plain
  # Remove references to the SSLSocket and Context
  self.sock.sslsock.close
  self.sock.sslsock = nil
  self.sock.sslctx  = nil
  self.sock.sslhash = nil
  self.sock = self.sock.fd
  self.sock.extend(::Rex::Socket::Tcp)
end

#unicode_filter_decode(str) ⇒ Object

Decodes (or not) a UTF-8 string



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# File 'lib/rex/post/meterpreter/client.rb', line 404

def unicode_filter_decode(str)
  self.encode_unicode ? Rex::Text.unicode_filter_decode(str) : str
end

#unicode_filter_encode(str) ⇒ Object

Encodes (or not) a UTF-8 string



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# File 'lib/rex/post/meterpreter/client.rb', line 397

def unicode_filter_encode(str)
  self.encode_unicode ? Rex::Text.unicode_filter_encode(str) : str
end