RE: Windows 2000 password policy bypass possibility

["Bradley, Tony" <tony.bradley () eds com>]

The password history check *should* still be performed from what I know, but
it is possible for a user to simply go through and change their password 18
times so they can use the old one again.

To combat this you also need to set a minimum password age in your policy.
If you set the minimum password age to 1 month they will not be able to
reset their password for at least 1 month each time and then you guarantee
that it will be 18 months until they can re-use the old password again.

Tony Bradley, MCSE, MCSA, MCP, A+
Threat & Vulnerability Monitor
EDS GM Global Information Protection Programme

"The price of success is hard work, dedication to the job at hand, and the
determination that whether we win or lose, we have applied the best of
ourselves to the task at hand."  ~ Vince Lombardi ~

  



-----Original Message-----
From: Leonid Mamtchenkov [mailto:leonid () francoudi com]
Sent: Thursday, March 07, 2002 2:41 AM
To: bugtraq () securityfocus com
Subject: Windows 2000 password policy bypass possibility


Hello All,

I have noticed the following behavior with Windows 2000 and I am not
yet sure whether that is a bug or a feature.

It is possible to create a security policy regarding passwords for
Windows 2000, that will require users to use secure passwords, which
should be periodically changed.  It is also possible to make Windows
remember several previous passwords (18 in our case).

Now, when time comes for user to change the password, system checks
whether or not new password is among those 18 old ones.  If it is not,
and password satisfies other conditions, then password changes.

It is possible for user though to change the password without waiting
for it to expire.  When changing this password, password history check
is not done, but check for all other conditions is performed.

Is this issue serious enough to be forwarded to Microsoft, or is it
supposed to work this way?

-- 
Best regards,
  Leonid Mamtchenkov, RHCE
  System Administrator
  Francoudi & Stephanou Ltd.