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_ctx =

Cached SSL certificate (required to scale)

nil
@@ssl_mutex =

Mutex to synchronize class-wide operations

::Mutex.new

Constants included from PacketDispatcher

PacketDispatcher::PacketTimeout

Instance Attribute Summary collapse

Attributes included from ChannelContainer

#channels

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, #monitor_socket, #monitor_stop, #notify_response_waiter, #receive_packet, #register_inbound_handler, #remove_response_waiter, #send_packet, #send_packet_wait_response, #send_request

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 259

def method_missing(symbol, *args)
  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 373

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 381

def capabilities
  @capabilities
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 356

def ext
  @ext
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 364

def response_timeout
  @response_timeout
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 368

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 360

def sock
  @sock
end

#target_id ⇒ Object

The unique target identifier for this payload



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# File 'lib/rex/post/meterpreter/client.rb', line 377

def target_id
  @target_id
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 245

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) ⇒ 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 273

def add_extension(name)
  # 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
  ext.aliases.each_value do | extension |
    extension.cleanup if extension.respond_to?( 'cleanup' )
  end
  dispatcher_thread.kill if dispatcher_thread
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 303

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 334

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 341

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 310

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 177

def generate_ssl_context
  @@ssl_mutex.synchronize do 
  if not @@ssl_ctx
  
  wlog("Generating SSL certificate for Meterpreter sessions")

  key  = OpenSSL::PKey::RSA.new(1024){ }
  cert = OpenSSL::X509::Certificate.new
  cert.version = 2
  cert.serial  = rand(0xFFFFFFFF)

  subject = OpenSSL::X509::Name.new([
      ["C","US"],
      ['ST', Rex::Text.rand_state()],
      ["L", Rex::Text.rand_text_alpha(rand(20) + 10)],
      ["O", Rex::Text.rand_text_alpha(rand(20) + 10)],
      ["CN", self.sock.getsockname[1] || Rex::Text.rand_hostname],
    ])
  issuer = OpenSSL::X509::Name.new([
      ["C","US"],
      ['ST', Rex::Text.rand_state()],
      ["L", Rex::Text.rand_text_alpha(rand(20) + 10)],
      ["O", Rex::Text.rand_text_alpha(rand(20) + 10)],
      ["CN", Rex::Text.rand_text_alpha(rand(20) + 10)],
    ])

  cert.subject = subject
  cert.issuer = issuer
  cert.not_before = Time.now - (3600 * 365) + rand(3600 * 14)
  cert.not_after = Time.now + (3600 * 365) + rand(3600 * 14)
  cert.public_key = key.public_key
  ef = OpenSSL::X509::ExtensionFactory.new(nil,cert)
  cert.extensions = [
    ef.create_extension("basicConstraints","CA:FALSE"),
    ef.create_extension("subjectKeyIdentifier","hash"),
    ef.create_extension("extendedKeyUsage","serverAuth"),
    ef.create_extension("keyUsage","keyEncipherment,dataEncipherment,digitalSignature")
  ]
  ef.issuer_certificate = cert
  cert.add_extension ef.create_extension("authorityKeyIdentifier", "keyid:always,issuer:always")
  cert.sign(key, OpenSSL::Digest::SHA1.new)

  ctx = OpenSSL::SSL::SSLContext.new(:SSLv3)
  ctx.key = key
  ctx.cert = cert

  ctx.session_id_context = Rex::Text.rand_text(16)

  wlog("Generated SSL certificate for Meterpreter sessions")
  
  @@ssl_ctx = ctx
  
  end # End of if not @ssl_ctx
  end # End of mutex.synchronize
  
  @@ssl_ctx
end

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

Initializes the meterpreter client instance



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# File 'lib/rex/post/meterpreter/client.rb', line 97

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


  # 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

#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 318

def register_extension_alias(name, ext)
  self.ext_aliases.aliases[name] = 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 325

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 126

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)

  if not ssl.respond_to?(:accept_nonblock)
    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

  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 168

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 = self.sock.fd
  self.sock.extend(::Rex::Socket::Tcp)
end