RE: Password complexity - improvement



OK- time for "real world thinking" to be applied ;)

First off, Ansgar is completely correct - I was wrong to poke fun.
Requiring aspects of complexity does indeed limit the possible passwords
in that, say, "May I momma dogface to the banana patch?" could never be
used.

While no restrictions on a password policy would always allow for mixed
case alphanumeric (and specials characters) to be used, having a policy
in place "forces" them to be used. In this case, the fact that you have
"reduced possible passwords" does not matter in the least, as all BF
efforts or rainbow table generation would *require* that all possible
combinations still be used since you don't know where in the phrase what
characters were being used. If the point is that you could "drop out"
certain characters strings while doing a BF or RT generation in the case
that you knew the password policy being used in order to speed up the
process, I would argue that generating the string, then looking at it to
see if it is complex enough to be hashed and compared would take longer
than just hashing and comparing in the first place.

That being said, forcing password complexity ensures that a minimum
keyspace be used (as opposed to just hoping) and thus has a positive
impact on security regardless of what "the math says" in regard to
reducing possible (and weaker) passphrases.

t



-----Original Message-----
From: listbounce@xxxxxxxxxxxxxxxxx
[mailto:listbounce@xxxxxxxxxxxxxxxxx] On Behalf Of John Wienand
Sent: Thursday, August 16, 2007 11:06 AM
To: Jackson, Eric R IT3 (CVN75 CS-3)
Cc: Ansgar -59cobalt- Wiechers; focus-ms@xxxxxxxxxxxxxxxxx;
listbounce@xxxxxxxxxxxxxxxxx
Subject: RE: Password complexity - improvement

I think you are arguing two different points here.

One is the number of possible passwords and the other is
negative impacts on security.

He is correct when he says it reduces the number of
passwords, but incorrect when he says it diminishes
security.

In the example you give below, if all four aspects are
enforced, then the second password could not be used. This
does in fact "reduce the number of possible passwords".

Another example would be the difference between requiring
that a password be exactly 8 characters in length, and
allowing a password to be any length up to 8 characters.
The latter would allow for a lot more possible combinations,
but does not remove the fact that a 1 character password is
not nearly as secure.

Just my 2 cents.

John Wienand
Network Services Manager
BNA Software
O: 202-496-6001 C: 202 329-1095



"Jackson,
Eric R IT3
(CVN75 To
CS-3)" "Ansgar -59cobalt-
<jackser@cv Wiechers"
n75.navy.mi <bugtraq@xxxxxxxxxxxxxxxx>
l> cc
Sent by: <focus-ms@xxxxxxxxxxxxxxxx
listbounce@ m>
securityfoc Subject
us.com RE: Password complexity -
improvement

08/15/2007
06:46 PM







Ansgar,

You're absolutely wrong in your statement here. Enforcing
passwords
that MUST consist of uppercase letters, lowercase letter,
numbers AND
special characters INCREASES the total number of possible
passwords;
which in turn has a positive impact on your security.

It is much harder to break a password of AaBb1! than aabb1!
The more
options there are that are enforced, the more complex the
passwords.
The determining factor in this case would be how long or
short the
password lengths are.

R/
Jackson

-----Original Message-----
From: listbounce@xxxxxxxxxxxxxxxxx
[mailto:listbounce@xxxxxxxxxxxxxxxxx]
On Behalf Of Ansgar -59cobalt- Wiechers
Sent: Wednesday, August 15, 2007 2:39 PM
To: focus-ms@xxxxxxxxxxxxxxxxx
Subject: Re: Password complexity - improvement

On 2007-08-15 dubaisans dubai wrote:
Is there a way to improve the password complexity
requirements in
Windows 2000/2003 servers

The default will enforce 3 of the following 4 properties -
Uppercase,
smallercase, numbers, special-characters.

Is there a way to enforce all 4 properties.

Enforcing passwords that MUST consist of uppercase letters,
lowercase
letters, numbers AND special characters reduces the total
number of
possible passwords, which in consequence has a negative
impact on your
security.

Regards
Ansgar Wiechers
--
"All vulnerabilities deserve a public fear period prior to
patches
becoming available."
--Jason Coombs on Bugtraq






Relevant Pages

  • RE: Passwords: length vs. complexity (was: How does the Cain and Abel SAM dump works?)
    ... this web site, a normal English word has about 5 characters, so using 2 words ... system to enforce a minimum of 15 characters then a very good complexity. ... The fact is, for character to character, if you add 1 key space (add ... Merely enforcing password length will gain you nothing. ...
    (Security-Basics)
  • RE: Password complexity requirements
    ... Microsoft recommends that you require the use ... To enforce password complexity in your organization, ... Password must meet complexity requirements security setting. ... English uppercase characters. ...
    (microsoft.public.win2000.security)
  • Re: Passwords: length vs. complexity
    ... characters in it, but by the number of tokens. ... Although that probably still is secure enough, ... Enforcing long passwords also may lead to notes with passwords left ... approach effectively increases the complexity rather than the length. ...
    (Security-Basics)
  • RE: Password complexity - improvement
    ... One is the number of possible passwords and the other is ... negative impacts on security. ... allowing a password to be any length up to 8 characters. ... Enforcing passwords that MUST consist of uppercase letters, ...
    (Focus-Microsoft)
  • RE: ADS Password Storage Protection-$100 reward to crack my password hashes
    ... characters and do character substitution using words instead of letters ... when doing a dictionary attack. ... complexity in their passphrase. ... Clues Normal Password Cracker Would Not Have: ...
    (Security-Basics)