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Posted by =?Utf-8?B?QW50ZWF1cw==?= on September 3, 2007, 5:10 pm
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Not a solution, but I 've always thought Windows' default security policies
were daft, what with having faddist password-change requirements, yet NO
protection against dictionary attack, and NO way of identifying or closing
disused accounts.
It stands to reason that any system which permits remote access MUST have a
limit to the number of password-entry attempts in a given period, otherwise a
correct guess is inevitable given enough time. Yet, while windows has this
capability it's (inexplicably) turned off by default. Even though turning it
on has no significant impact on system useability. Why not, for heavens sake?
Disused accounts represent a serious security problem, especially with many
sites now granting remote access, thus there may be any number of
remotely-accessible accounts lying open for which the user has long-since
left the company, but for which the personnel dept just plumb forgot to tell
I.T. about. Yet, Windows provides NO way of closing accounts which have not
been used for a substantial time, which would seem to be one of the most
sensible and basic precautions to take against this occurrence.
The other side of this is that despite its laxness in other respects,
Windows sets a 42-day password-expiry policy, and worse, does so 'silently'
without telling anyone it's done so. This is extremely bad.
I've had cases where laptops in overseas locations have unexpectedly
demanded a password-change in situations where there was no way to rejoin the
domain within the time limit. This effectively 'bricks' the laptop until it
can be shipped back to base. Highly embarrassing for me, and could have cost
the company an international deal.
It's time someone persuaded MS to see sense over these poorly thought-out
security policies.
1. Ditch password-expiry, or at least WARN the user that it exists, right
from first logon. (timebomb icon in sytem tray?)
2. Set password-lockout (dictionary-attack protection) ON by default.
3. Provide a means to identify/close disused accoutns.
Just my two cents worth.
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Posted by Steve Riley [MSFT] on September 3, 2007, 5:59 pm
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Account lockout is a poor substitute for good passwords -- and is one of the
most expensive security features you can use. Let's think about this by
considering the threat. What threat does account lockout (attempt to)
mitigate? Password guessing. How can you make password guessing attacks
become useless for an attacker? Two ways: implement lockouts or use good
(meaning long) passwords.
Consider the first choice, account lockouts. The typical cost to an
organization to reset locked accounts is US$75 per help desk call. In a
medium or large organization, this can become a very high monthly
maintenance cost. In nearly all instances, the call results from users
locking themselves out (too many vodka tonics on the plane, maybe?), not
users encountering locked out accounts because some bad guy was trying to
guess passwords. Account lockouts have one more -- very bad -- problem: they
*create* opportunities for bad guys to conduct denial-of-service attacks
against accounts or entire domains! Even if you use a timed unlock of, say,
15 minutes, then the attacker can write his script to churn through
thousands of bogus logon attempts every 15 minutes 2 seconds. So, contrary
to your claim, enabling this setting actually can have significant impact on
usability.
Account lockout is there for people who absolutely need it. But I can't
think of any instance where this is true. Instead, have a policy that
requires simple passwords at least 15 characters long. Forget about
complexity rules that force people to write down passwords. A simple
15-character passphrase (think short sentence) is easy to remember, quick to
type, and far stronger than any short complex password. A passphrase like
this will withstand any kind of automated password attack, including those
based on rainbow tables. And you can even use a method that helps you
remember unique phrases for each site, if you wish:
web mail: "my dog and i got the mail"
shopping: "my dog and i bought some stuff"
office: "my dog and i went to work"
porn site: "my dog and i admired some art"
This is why we disable account lockout by default. There are much better --
and much less expensive -- ways to mitigate the threat.
You're right, there's no built-in method to automatically disable unused
accounts. A variety of third-party products can provide you with this
functionality. I suspect some of them might be free, perhaps simple scripts
even. I tried searching on "automatically disable unused accounts" and saw a
few hits that looked promising. This particular function, however, rightly
belongs in the HR process. A number of customers I've spoken with have
automated the account creation/disablement/deletion process, incorporating
it into HR systems. When a new user is hired, the account is created; when
the user departs, the account is disabled; some time later, it's deleted.
The HR systems take care of this, not domain or enterprise administrators. I
wrote more about this subject here:
http://blogs.technet.com/steriley/archive/2007/05/31/when-you-say-goodbye-to-an-employee.aspx
Password expiration is an important setting for everyone. It mitigates two
threats: employees sharing passwords and bad guys discovering passwords.
Because we can eliminate the second threat using long simple passphrases as
I described above, then we have only one remaining threat: password sharing.
Your estimation of how prevalent this threat is in your environment will
guide you toward choosing an expiration time that works for you. 42 days is
a reasonable default; our own corpnet uses 70 days. My experience with most
customers shows that password sharing isn't a problem. So for those who do
enforce long simple passphrases, I suggest that a reasonable default for
expiration is 120 days.
Windows begins notifying you 14 days before your password expires. You can
change this time period through group policy. I was in a similar situation
recently. Last month my domain password expired while I was in Australia for
TechEd there. I could continue to log on to my laptop with cached
credentials (so I'm not sure why you say your laptops become bricked?), but
couldn't use Outlook Web Access or RPC+HTTP of course. So I connected to a
Terminal Server computer we have on the Internet, logged on there, and
changed my password.
--
Steve Riley
steve.riley@microsoft.com
http://blogs.technet.com/steriley
http://www.protectyourwindowsnetwork.com
> Not a solution, but I 've always thought Windows' default security
> policies
> were daft, what with having faddist password-change requirements, yet NO
> protection against dictionary attack, and NO way of identifying or closing
> disused accounts.
>
> It stands to reason that any system which permits remote access MUST have
> a
> limit to the number of password-entry attempts in a given period,
> otherwise a
> correct guess is inevitable given enough time. Yet, while windows has
> this
> capability it's (inexplicably) turned off by default. Even though turning
> it
> on has no significant impact on system useability. Why not, for heavens
> sake?
>
> Disused accounts represent a serious security problem, especially with
> many
> sites now granting remote access, thus there may be any number of
> remotely-accessible accounts lying open for which the user has long-since
> left the company, but for which the personnel dept just plumb forgot to
> tell
> I.T. about. Yet, Windows provides NO way of closing accounts which have
> not
> been used for a substantial time, which would seem to be one of the most
> sensible and basic precautions to take against this occurrence.
>
> The other side of this is that despite its laxness in other respects,
> Windows sets a 42-day password-expiry policy, and worse, does so
> 'silently'
> without telling anyone it's done so. This is extremely bad.
>
> I've had cases where laptops in overseas locations have unexpectedly
> demanded a password-change in situations where there was no way to rejoin
> the
> domain within the time limit. This effectively 'bricks' the laptop until
> it
> can be shipped back to base. Highly embarrassing for me, and could have
> cost
> the company an international deal.
>
> It's time someone persuaded MS to see sense over these poorly thought-out
> security policies.
>
> 1. Ditch password-expiry, or at least WARN the user that it exists, right
> from first logon. (timebomb icon in sytem tray?)
>
> 2. Set password-lockout (dictionary-attack protection) ON by default.
>
> 3. Provide a means to identify/close disused accoutns.
>
>
> Just my two cents worth.
>
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Posted by Steve Riley [MSFT] on September 4, 2007, 12:46 am
If you were Registered and logged in, you could reply and use other advanced thread options
Microsoft servers, never saw it arrive there...}
Account lockout is a poor substitute for good passwords -- and is one of the
most expensive security features you can use. Let's think about this by
considering the threat. What threat does account lockout (attempt to)
mitigate? Password guessing. How can you make password guessing attacks
become useless for an attacker? Two ways: implement lockouts or use good
(meaning long) passwords.
Consider the first choice, account lockouts. The typical cost to an
organization to reset locked accounts is US$75 per help desk call. In a
medium or large organization, this can become a very high monthly
maintenance cost. In nearly all instances, the call results from users
locking themselves out, not users encountering locked out accounts because
some bad guy was trying to guess passwords. Account lockouts have one
more -- very bad -- problem: they *create* opportunities for bad guys to
conduct denial-of-service attacks against accounts or entire domains! Even
if you use a timed unlock of, say, 15 minutes, then the attacker can write
his script to churn through thousands of bogus logon attempts every 15
minutes 2 seconds. So, contrary to your claim, enabling this setting
actually can have significant impact on usability.
Account lockout is there for people who absolutely need it. But I can't
think of any instance where this is true. Instead, have a policy that
requires simple passwords at least 15 characters long. Forget about
complexity rules that force people to write down passwords. A simple
15-character passphrase (think short sentence) is easy to remember, quick to
type, and far stronger than any short complex password. A passphrase like
this will withstand any kind of automated password attack, including those
based on rainbow tables. And you can even use a method that helps you
remember unique phrases for each site, if you wish:
* web mail: "my dog and i got the mail"
* shopping: "my dog and i bought some stuff"
* office: "my dog and i went to work"
* photo site: "my dog and i admired some art"
This is why we disable account lockout by default. There are much better --
and much less expensive -- ways to mitigate the threat.
You're right, there's no built-in method to automatically disable unused
accounts. A variety of third-party products can provide you with this
functionality. I suspect some of them might be free, perhaps simple scripts
even. I tried searching on "automatically disable unused accounts" and saw a
few hits that looked promising. This particular function, however, rightly
belongs in the HR process. A number of customers I've spoken with have
automated the account creation/disablement/deletion process, incorporating
it into HR systems. When a new user is hired, the account is created; when
the user departs, the account is disabled; some time later, it's deleted.
The HR systems take care of this, not domain or enterprise administrators. I
wrote more about this subject here:
http://blogs.technet.com/steriley/archive/2007/05/31/when-you-say-goodbye-to-an-employee.aspx
Password expiration is an important setting for everyone. It mitigates two
threats: employees sharing passwords and bad guys discovering passwords.
Because we can eliminate the second threat using long simple passphrases as
I described above, then we have only one remaining threat: password sharing.
Your estimation of how prevalent this threat is in your environment will
guide you toward choosing an expiration time that works for you. 42 days is
a reasonable default; our own corpnet uses 70 days. My experience with most
customers shows that password sharing isn't a problem. So for those who do
enforce long simple passphrases, I suggest that a reasonable default for
expiration is 120 days.
Windows begins notifying you 14 days before your password expires. You can
change this time period through group policy. I was in a similar situation
recently. Last month my domain password expired while I was in Australia for
TechEd there. I could continue to log on to my laptop with cached
credentials (so I'm not sure why you say your laptops become bricked?), but
couldn't use Outlook Web Access or RPC+HTTP of course. So I connected to a
Terminal Server computer we have on the Internet, logged on there, and
changed my password.
--
Steve Riley
steve.riley@microsoft.com
http://blogs.technet.com/steriley
http://www.protectyourwindowsnetwork.com
> Not a solution, but I 've always thought Windows' default security
> policies
> were daft, what with having faddist password-change requirements, yet NO
> protection against dictionary attack, and NO way of identifying or closing
> disused accounts.
>
> It stands to reason that any system which permits remote access MUST have
> a
> limit to the number of password-entry attempts in a given period,
> otherwise a
> correct guess is inevitable given enough time. Yet, while windows has
> this
> capability it's (inexplicably) turned off by default. Even though turning
> it
> on has no significant impact on system useability. Why not, for heavens
> sake?
>
> Disused accounts represent a serious security problem, especially with
> many
> sites now granting remote access, thus there may be any number of
> remotely-accessible accounts lying open for which the user has long-since
> left the company, but for which the personnel dept just plumb forgot to
> tell
> I.T. about. Yet, Windows provides NO way of closing accounts which have
> not
> been used for a substantial time, which would seem to be one of the most
> sensible and basic precautions to take against this occurrence.
>
> The other side of this is that despite its laxness in other respects,
> Windows sets a 42-day password-expiry policy, and worse, does so
> 'silently'
> without telling anyone it's done so. This is extremely bad.
>
> I've had cases where laptops in overseas locations have unexpectedly
> demanded a password-change in situations where there was no way to rejoin
> the
> domain within the time limit. This effectively 'bricks' the laptop until
> it
> can be shipped back to base. Highly embarrassing for me, and could have
> cost
> the company an international deal.
>
> It's time someone persuaded MS to see sense over these poorly thought-out
> security policies.
>
> 1. Ditch password-expiry, or at least WARN the user that it exists, right
> from first logon. (timebomb icon in sytem tray?)
>
> 2. Set password-lockout (dictionary-attack protection) ON by default.
>
> 3. Provide a means to identify/close disused accoutns.
>
>
> Just my two cents worth.
>
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Posted by Roger Abell [MVP] on September 4, 2007, 11:22 am
If you were Registered and logged in, you could reply and use other advanced thread options > Not a solution, but I 've always thought Windows' default security
> policies
> were daft, what with having faddist password-change requirements, yet NO
faddist ?
> protection against dictionary attack, and NO way of identifying or closing
> disused accounts.
>
Thinks about it. What Windows implements needs to work in all the
environments where Windows is deployed. Think of implementing
"protection against dictionary attack" (whatever you may have in mind
there other than tracking the rate of failed login attempts) or determining
what is "unused" in a large, global AD deployment.
Combine the result from that sofware design thought experiment with
the need to pivot results via a central, FSMO if you will, clearinghouse
(i.e. one in the world for that global AD).
Finally, look at the cost of such and compare that with the movement of
environments toward two-factor authentication methods (i.e. the cost of
providing compared to the believed inherent problems in the authN creds
it is designed to safeguard).
> It stands to reason that any system which permits remote access MUST have
> a
> limit to the number of password-entry attempts in a given period,
> otherwise a
> correct guess is inevitable given enough time. Yet, while windows has
> this
> capability it's (inexplicably) turned off by default. Even though turning
> it
"inexplicably" ?? MS mentions many times that usability studies have
shown it is not used due to the high cost that results at the helpdesk.
> on has no significant impact on system useability. Why not, for heavens
> sake?
>
Actually, turning it on has an impact on system overheads, particularly for
a globally dispersed AD deployment. The lockout is handled by the PDC
FSMO and relies on the lesser known feature, urgent replication.
> Disused accounts represent a serious security problem, especially with
> many
> sites now granting remote access, thus there may be any number of
> remotely-accessible accounts lying open for which the user has long-since
> left the company, but for which the personnel dept just plumb forgot to
> tell
> I.T. about. Yet, Windows provides NO way of closing accounts which have
> not
> been used for a substantial time, which would seem to be one of the most
> sensible and basic precautions to take against this occurrence.
>
I find that compromised accounts are at least as big of a problem, that is,
accounts that have "fallen into" the wrong hands. Password change is the
built-in mechanism to periodically invalidate these accesses. The accounts
are seen as in use and very possibly in an expected use pattern, so
disabling
due to login failures, due to non-use, due to use attempting to access areas
unauthorized for the account, etc. all would not see a problem; yet the
account
may be in use for info theft for extended periods.
> The other side of this is that despite its laxness in other respects,
> Windows sets a 42-day password-expiry policy, and worse, does so
> 'silently'
> without telling anyone it's done so. This is extremely bad.
>
?? Most admins I know go over these settings adjusting to their shop's
standards and users are provided with pwd change notices for a time
period that is configurable. What are you wanting to see happen?
> I've had cases where laptops in overseas locations have unexpectedly
> demanded a password-change in situations where there was no way to rejoin
> the
> domain within the time limit. This effectively 'bricks' the laptop until
> it
> can be shipped back to base. Highly embarrassing for me, and could have
> cost
> the company an international deal.
>
I really do not follow the scenario. The cached login would not be
demanding a password change.
> It's time someone persuaded MS to see sense over these poorly thought-out
> security policies.
>
AFAIK they have for a long, long time been advising people to
move away from password based authentication.
> 1. Ditch password-expiry, or at least WARN the user that it exists, right
> from first logon. (timebomb icon in sytem tray?)
>
> 2. Set password-lockout (dictionary-attack protection) ON by default.
>
1+2 ditch passwords
> 3. Provide a means to identify/close disused accoutns.
>
look into two-factor identity credentials forms and their mgmt capabilities
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Posted by John Brown on September 16, 2007, 12:15 pm
If you were Registered and logged in, you could reply and use other advanced thread options
OUrganizeIT ( www.synergix.com ) to address a different operational issue
(managing computer and user objects in AD), however, over the course of time
added a feature to update the account expiration attribute of the user
object. You can not set the value to 1 or 7 days and be assured that that
account will be secured if there is not activity on that user object. No
software is installed on DCs
Other issue is when dealing with VPN users who log in with cached
credentials. We can still manage the computer object and user object much
like they were LAN connected and also have tackled the password change issue
which is a major problem managing for VPN users (unless you use VPN software
GINA)
J
> My apologies if I'm not posting in the correct newsgroup. My question is
> if
> there's a way to set up a security policy on Windows 2003 DC which is
> lockout
> or disable a user that dosn't log into the domain for a specified amount
> of
> time. For example a user that hasn't logged into the domain for 30 days
> will
> be locked out???
>
> Thanks
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