bugtraq - Re: Apache web server 2.2: htpasswd predictable salt weakness

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Date: Fri, 15 Feb 2008 20:44:08 +0300
From: 3APA3A <3APA3A@...URITY.NNOV.RU>
To: Peter Watkins <peterw@....net>
Cc: bugtraq@...urityfocus.com
Subject: Re: Apache web server 2.2: htpasswd predictable salt weakness

Dear Peter Watkins,

--Thursday, February 14, 2008, 5:55:17 AM, you wrote to bugtraq@...urityfocus.com:

PW> As a result:
PW>  - Salts created by htpasswd are very predictable. 
PW>  - The universe of salts for htpasswd is far less than the MD5 algorithm
PW>    provides for -- 29 bits vs. 48, or 0.000191 percent of the range that
PW>    should be used for MD5.

As  far  as I understand, salt predictability gives nothing to you. Salt
protects  against  rainbow  tables  attacks in case stored passwords are
stolen. Salt is stored with password, that is salt is known to attacker.
All you need for salt is to be different for different passwords and for
different  systems.  That is 175, 176, 177 etc are pretty good salts for
sequentially generated passwords in case 175 is apriory unknown.

Salt universe is more important, but 29 bits against 48 is not something
scaring.

May be I am missing something?

-- 
~/ZARAZA http://securityvulns.com/