WebApp Sec mailing list archives
Re: Script Based Attacks & Form Hacks
From: Vicente Aguilera <vaguilera () isecauditors com>
Date: Fri, 22 Jul 2005 09:46:56 +0200
Hi, CAPTCHA is a good solution to prevent automatic form submissions, but:"Greg Mori and Jitendra Malik of the University of California at Berkeley have written a program that can solve ez-gimpy with accuracy 83% (see Breaking a Visual CAPTCHA for details). Thayananthan, Stenger, Torr, and Cipolla of the Cambridge vision group have written a program that can achieve 93% correct recognition rate against ez-gimpy..." (www.captcha.net)
If you use CAPTCHA, CAPTCHA-PIX is probably the best option.We have to remember that CAPTCHA does not guarantee the security. The implementation and the validation also must be realized correctly.
To prevent automatic form submissions in login forms you can also use: 1. One-time-logins/One-time-passwordsFor example, if the user password is: "a34.;(vad78!$" the application can ask for the password: "Put the character 1,5,2,6,8,9,10,4 of your password", and these positions could change randomly.
2. Account lock For example after 5 unsuccessful attempts. Vicente Aguilera DÃaz OPST, OPSA, ITIL vaguilera () isecauditors com Paul Kurczaba escribió:
To prevent automatic form submissions I use a custom written implementation of CAPTCHA (http://www.captcha.net/). This prevents robots from automatically setting up accounts. Many web developers do use client side JavaScript for controlling form submission data (ex. making sure all text boxes are filled, verifying email address structure, etc.) This is unprofessional and (could be) insecure. The form verification should be done on the server side.The following page I have set up: http://www.securinews.com/login/register.htmuses CAPTCHA to help prevent automatic submissions. If the CAPTCHA string is not entered, the form will not be processed by the server. You are free to create a Java program to test bypassing CAPTCHA.-Paul Chad Maniccia wrote:Hi List, One thing I have not heard any one discuss is the use of automated scripts and form hacking. I could easily write a Java program to attack any ASP,JSP,PHP etc.. simply by viewing the page source to find the parameters the form processor will be looking for. You could use this to fill up some ones database with garbage bring the server to a standstill or worse yet bypass all the fancy javascript you had on the calling page. Some web applications actually use javascript to calcualte currency transactions. What ideas do you guys have to protect yourself from these? Thanks, Chad
Current thread:
- Re: Script Based Attacks & Form Hacks, (continued)
- Re: Script Based Attacks & Form Hacks Saqib Ali (Jul 21)
- Re: Script Based Attacks & Form Hacks Stephen de Vries (Jul 22)
- Re: Script Based Attacks & Form Hacks Saqib Ali (Jul 22)
- RE: Script Based Attacks & Form Hacks Serghei S. (Jul 22)
- RE: Script Based Attacks & Form Hacks Paul Laudanski (Jul 24)
- Re: Script Based Attacks & Form Hacks Stephen de Vries (Jul 22)
- Re: Script Based Attacks & Form Hacks leighm (Jul 21)
- Re: Script Based Attacks & Form Hacks Christopher J Varenhorst (Jul 21)
- Re: Script Based Attacks & Form Hacks Stephen de Vries (Jul 22)
- Re: Script Based Attacks & Form Hacks Paul Kurczaba (Jul 21)
- Re: Script Based Attacks & Form Hacks Sean Utt (Jul 22)
- Re: Script Based Attacks & Form Hacks Vicente Aguilera (Jul 22)
- Re: Script Based Attacks & Form Hacks Andrew van der Stock (Jul 22)
- Re: Script Based Attacks & Form Hacks Stephen de Vries (Jul 22)
- Re: Script Based Attacks & Form Hacks Vicente Aguilera (Jul 22)
- Re: Script Based Attacks & Form Hacks Stephen de Vries (Jul 23)
- Re: Script Based Attacks & Form Hacks Christian Martorella (Jul 23)
- Re: Script Based Attacks & Form Hacks Saqib Ali (Jul 21)
- RE: Script Based Attacks & Form Hacks Jose Varghese (Jul 22)