AW: ADS Password Storage Protection

[Christian.Assfalg () bc boehringer-ingelheim com]

Do you have a link to those password papers from Microsoft? Sounds interresting.

Recently, I attended a lenghthy debate about single-sign on from a couple of people who don't feel the need to lock 
their workstations when they go, or who feel they need to be able to let other people work with THEIR accounts... 
(without fear of having them access to some "personal" data, which is what the single-sign on solution was used for)
Yet, I don't necessarily mean single-sign on, more like a single account, single credentials you can use instead of all 
those simple and small web-accounts... Most of the time, I can't even remember what username it was, especially if it's 
crowded (ebay, big forums...) so I can't use my "default" username or if you're given you a customer number.

I agree, it has additional Risks, but a lot of pros, too. You can change your password consistently for a great number 
of access points for example. In the long run, I think that protects you better. Your solution with different endings 
is not too bad, but as soon as you change your root (and I guess you do, or at least should sometime), you don't know 
which root you have to use for a site you haven't visited for half a year. And of course if someone knows one of your 
passwords and suspects this technique, your're in trouble.

However... Just had an idea: what about using some sort of hash as password...? Something like you do with root+ending, 
but using the hash of that as password, maybe incorporating the username or so? That should protect your "root" quite a 
bit, and it is easily reproducable if you use a common hash-function like sha-1 or md5... One could write a plug-in for 
Firefox for example to make it easy to use.

And it would give you reasonable complexity and length, not matter what the password / passphrase you need to remember 
is. Though md5sum and sha1sum only contain lowercase letters and numbers.


-----Ursprüngliche Nachricht-----
Von: Roger A. Grimes [mailto:roger () banneretcs com] 
Gesendet: Donnerstag, 20. Juli 2006 16:56
An: Assfalg,Christian (APER) BIP-DE-B
Betreff: RE: ADS Password Storage Protection


There are many that feel an english word passphrase is significantly weaker than a much shorter complex password. 
Microsoft's Great Password Debate papers are a great starting point. I just disagree with the conclusions because there 
are no good brute forcing tools for passphrases at the moment.

Single sign-on solutions, like Microsoft's Passport, have many additional risks.

What I do instead is to use a common root (say frog) with different endings for each web site (i.e. frogwebex, 
frogstock, etc.) so that my passwords are long, easy to remember, but different for each site. 

-----Original Message-----
From: Christian.Assfalg () bc boehringer-ingelheim com [mailto:Christian.Assfalg () bc boehringer-ingelheim com] 
Sent: Thursday, July 20, 2006 10:38 AM
To: Roger A. Grimes; security-basics () securityfocus com
Subject: AW: ADS Password Storage Protection

Your point against dumb complexity requirements is good. ;-) Just did a couple of calculations myself...
There are thousands of words in the english language I guess, so even if you use only 6 words, that still accounts for 
more possibilities than a random-character based password with 6-10 characters and only tens or some hundred 
possibilities per character.


Anyway - What I'd like to see is some way to get rid of all those different login credentials in the first place...

I mean just how many login credentials can you remember? How often have you searched for some username/password 
combination in your mailbox or so for a website you registered half a year ago and never visited since? How realistic 
is it to have a different, High-Quality password for each of those sites?

Actually, giving it some second thoughts, Microsoft's passport service is quite interresting in this respect, though I 
don't know any details about it, and I don't simply thrust Microsoft either. ;-)



-----Ursprüngliche Nachricht-----
Von: Roger A. Grimes [mailto:roger () banneretcs com]
Gesendet: Donnerstag, 20. Juli 2006 15:09
An: Assfalg,Christian (APER) BIP-DE-B; security-basics () securityfocus com
Betreff: RE: ADS Password Storage Protection


Here is my statement: That password length is a better defender of passwords than complexity, character for character, 
and that length should at least be given equal treatment when creating strong passwords. 

Instead, most applications and web sites asking for a strong password will accept significantly shorter and weaker 
passwords than my 20-character password, but not accept my alpha-only 20-character password. What would I like to see 
as the outcome:

1. More web sites and applications that accept long passwords as acceptable, without requiring 3 out of 4 character set 
complexity.
2. Microsoft increase the maximum value of the min. password length, which is now at 14.
3. People to start to talk about length as a natural factor of complexity, and give it its due consideration.

Instead, people and web sites are requiring shorter, complex passwords, which are sure to fall before a longer password.

-----Original Message-----
From: Christian.Assfalg () bc boehringer-ingelheim com [mailto:Christian.Assfalg () bc boehringer-ingelheim com] 
Sent: Thursday, July 20, 2006 2:25 AM
To: Roger A. Grimes; security-basics () securityfocus com
Subject: AW: ADS Password Storage Protection

What you say is true, length increases the maximum number of possible passwords far more than a greater number of base 
characters. That is statistical mathematics. However, it assumes that the characters are not dependant on the other 
characters, which is not always the case. That's why dictionary attacks work so fine. You can substitute a number of 
characters (say 4) with all possible 4-character-long words. That reduces your complexity quite a bit. A passphrase of 
8 words with 5 characters each does not translate to 24^40 possibilities, but rather to 
(whatever-the-number-of-5-character-words-in-english-is)^8. In a dictionary attack, you can use this to significantly 
reduce the number of tries you have to try.

That's why a lot of people don't think that passphrases are as good as passwords that have more random-character digits.

One point is shurely that the current cracking tools (this was mentioned before) concentrate on shorter, randomized 
passwords, instead of longer passphrases. This will eventually change, I guess.

Still, I think that you can make a cracker's work much more difficult if you use a long Sentence as password, adding a 
special character here and there. At least you can give quite some challenge to those who design the 
dictionary-creating algorithms. ;-)

However, all this discussion is based on the assumption that a cracker actually HAS the hash, and actually needs the 
clear-text password. As mentioned several times, you can aparently perfectly authenticate with the hash only by using a 
modified smb client. So why cracking the password at all?

I too think that you can enhance security much more by restricting access to these hashes. No hash, no way to crack the 
password somewhere else where you can't audit the failures and lock the account.



-----Ursprüngliche Nachricht-----
Von: Roger A. Grimes [mailto:roger () banneretcs com]
Gesendet: Dienstag, 18. Juli 2006 23:42
An: Eoin Miller
Cc: security-basics () securityfocus com
Betreff: RE: ADS Password Storage Protection


Here's my conjecture.

A 10 character password with 26 characters, 26^10 =146,813,779,479,510
possible passwords.

If my password is 9 characters long, I have to add another 12 characters
of complexity before I pass the increase of strength from lengthening my
password from 9 characters to 10.

When faced with whether to add more complexity or length to increase
password strength, length counts more than complexity, per the math,
character for character.

If you add the fact that even with increased complexity requirements,
80% of your users will use the same 32 characters anyway, increasing
complexity doesn't mean the passwords really get more complex and harder
to break. 

In an extreme example to further support my case, suppose the IT
department required four different character sets to be used in a
password with a min. length of 4. With most normal existing password
complexity requirement character sets I could meet the requirements with
a password of Pa5@.  This password would be broken relatively quickly.
If I require a min. length of 5 and three character sets (ex. Pass5),
the workload required would be more than with the latter than the
former.

-----Original Message-----
From: Eoin Miller [mailto:eoin.miller () trojanedbinaries com] 
Sent: Tuesday, July 18, 2006 4:55 PM
To: Roger A. Grimes
Cc: security-basics () securityfocus com
Subject: Re: ADS Password Storage Protection

Roger A. Grimes wrote:
> Length is always more important than complexity because password 
> keyspace is expressed as Y^X, where Y is the number of possible 
> characters and X is the password length. Thus, any similar increase in

> X has significantly more impact than to Y.
>
>   
Roger,

That relies upon the assumption of all attackers performing attacks that
attempt all possible characters all the time. In most attempts to break
passwords, the attacker will remove the uncommonly used characters from
being attempted. Since users try and follow the bare minimum
requirements, not adding complexity requirements can have a detrimental
effect. Consider the following hypothetical situation:

An internal employee has sniffed hashes from a network (we will assume
there are no shortcuts/weaknesses in the algorithm). The internal
company policy only requires 8 character length passwords and nothing
more. Which will be broken first by the attacker who is only trying to
crack a hash with lowercase letters [a-z]?

A hash generated from a 10 character password  that was created with
only lowercase [a-z].

or

A hash generated from a 8 character password that was created with
lowercase [a-z], uppercase [A-Z], numerical [0-9].

The likely combinations to guess are not only derived from the length of
the password but also from the minimum requirements instituted by the
password policy. Having password complexity requirements forces
attackers into using more possible combinations. I will not argue that
length or complexity is more important than the other because situations
can arise that expose the weakness of either. Both are required (and
complement each other) when instituting a sound password policy.

--Eoin

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This list is sponsored by: Norwich University

EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The NSA has designated Norwich University a center of Academic Excellence
in Information Security. Our program offers unparalleled Infosec management
education and the case study affords you unmatched consulting experience.
Using interactive e-Learning technology, you can earn this esteemed degree,
without disrupting your career or home life.

http://www.msia.norwich.edu/secfocus
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