CaptchaSecurityImages.php Denial Of Service

vendor:

CaptchaSecurityImages.php

by:

cp77fk4r

7,5

CVSS

HIGH

Denial Of Service

400

CWE

Product Name: CaptchaSecurityImages.php

Affected Version From: Unknown

Affected Version To: Unknown

Patch Exists: NO

Related CWE: N/A

CPE: N/A

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: N/A

Unknown

CaptchaSecurityImages.php Denial Of Service

The vulnerability exists in the CaptchaSecurityImages.php script, which is vulnerable to a Denial Of Service attack. An attacker can send a crafted request with large values for the width, height and characters parameters, which will cause the script to crash. To fix the vulnerability, the script should be modified to use constant values for the width, height and characters parameters.

Mitigation:

Delete all the "$_GET[x]" strings and make it constant.

Source

Exploit-DB raw data:

# Exploit Title: CaptchaSecurityImages.php Denial Of Service
# Author: cp77fk4r | empty0page[SHIFT+2]gmail.com | www.DigitalWhisper.co.il
# Software Link: http://www.white-hat-web-design.co.uk/articles/php-captcha.php
#
##[Denial Of Service]
(OWASP: The Denial of Service (DoS) attack is focused on making unavailable a resource (site, application, server) for the purpose it was designed. There are many ways to make a service unavailable for legitimate users by manipulating network packets, programming, logical, or resources handling vulnerabilities, among others. If a service receives a very large number of requests, it may stop providing service to legitimate users. In the same way, a service may stop if a programming vulnerability is exploited, or the way the service handles resources used by it.)
#
#Exploit:
/CaptchaSecurityImages.php?width=13333337&height=13333337&characters=13333337
#
#
The vuln code is: (lines 73-75)
#
$width = isset($_GET['width']) ? $_GET['width'] : '120';
$height = isset($_GET['height']) ? $_GET['height'] : '40';
$characters = isset($_GET['characters']) && $_GET['characters'] > 1 ? $_GET['characters'] : '6';
#
To fix it- delete all the "$_GET[x]" strings and make it constant, like this:
#
$width=100;
$height=40;
$characters=5;
#
#
#[e0f]