Not such a bad idea though in some ways. Put the sentence in a captcha
and it might become fairly hard to fake. However the operation could
strain short term memory; people would have to be writing their password
down all over the place. Let one of the slips of paper fall into the
wrong hands and the secret is out.
-----Original Message-----
From: Stephen de Vries [mailto:stephen@corsaire.com]
Sent: Friday, July 22, 2005 6:24 AM
To: Vicente Aguilera
Cc: webappsec@securityfocus.com
Subject: Re: Script Based Attacks & Form Hacks
Hi Vicente,
On 22 Jul 2005, at 07:46, Vicente Aguilera wrote:
To prevent automatic form submissions in login forms you can also use:
1. One-time-logins/One-time-passwords
For 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.
Perhaps I don't understand this solution, but it looks as though this
could be automated by a script. It would be fairly trivial to write
a script that parses the sentence "Put the character 1,5,2,6,8,9,10,4
of your password" and submits the correct characters from the
password to the login form...(?)
2. Account lock
For example after 5 unsuccessful attempts.
There is always the danger that an attacker could use this to lockout
all accounts on the system - which is also an effective DoS.
regards,
Stephen
Vicente Aguilera Díaz
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.htm
uses 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
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