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RE: looking for a webapp bruteforce video for non-techies
From: "Paul Melson" <pmelson () gmail com>
Date: Tue, 3 Jun 2008 13:01:05 -0400

That may not actually be such a bad password (on balance and in
context).  Sure it is a dictionary/leet word variant, but five
characters actually carry plenty of entropy (if mixed case and numerics
are also used).  However, if you have an authentication mechanism that
doesn't lock out an account and *allows* brute forcing, it doesn't
really matter how strong the password is; given enough
universe-lifetimes an attacker will always guess it eventually.

I second Martin's comment.  There's no point in talking to users about
password selection if the application doesn't A) lock the account after X
number of failed attempts *AND* B) force password expiration/rotation.
There's a very basic mathematical formula found in the Department of Defense
Password Management Guideline[1] that can be used to calculate the risk
associated with any particular password policy versus brute force guessing.
Definitely required reading for anyone designing or specifying a password
authentication mechanism.


[1] http://www.fas.org/irp/nsa/rainbow/std002.htm

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