RE: Minimum password requirements

["Roger A. Grimes" <roger () banneretcs com>]

Without knowing the value of your data and systems, the below
recommendations are inline with many people's/company's suggestions.

I don't see the most important recommendations, however.  You need to
add a minimum length and complexity requirements.  

The inactive account setting of 14 days may be a little too strict.

Consider disabling accounts as the first measure of inactivity, instead
of deleting them.  Also, consider do you back up the inactive system
account's files and email before deleting, or do you just delete?

If you have Windows systems, you should have the password a minimum
length of 6-8, although many security experts would recommend a minimum
length of 8 or even possibly 15 (passwords over 15 characters long
disable LM password hashing).

Also, use group policy or registry edits to disable LM password hashing
and force NTLMv2 authentication. 

In Windows, you also need to create a policy for dealing with password
changes of service accounts.  Service account passwords must be changed
in the Services console and in Active Directory/User Manager.

Lastly, think about how you will determine inactive accounts.  In
Windows, you need Windows Server 2003 domain controllers and be at
Windows 2003 domain functional level to be able trust the last logged on
timestamp.  

Roger

************************************************************************
***
*Roger A. Grimes, Banneret Computer Security, Computer Security
Consultant 
*CPA, CISSP, MCSE: Security (NT/2000/2003/MVP), CNE (3/4), A+
*email: roger () banneretcs com
*cell: 757-615-3355
*Author of Malicious Mobile Code:  Virus Protection for Windows by
O'Reilly
*http://www.oreilly.com/catalog/malmobcode
*Author of upcoming Honeypots for Windows (Apress)
************************************************************************
****



-----Original Message-----
From: Randall M Gunning [mailto:securityfocus () randygunning com] 
Sent: Thursday, July 15, 2004 11:27 AM
To: security-basics () securityfocus com
Subject: Minimum password requirements

I am working on implementing some minimum standards for our department.
I am wondering what the list thinks of these standards:

a. Passwords must be changed at least every 90 days.
b. Passwords cannot be changed for at least 14 days.
c. Previous passwords cannot be reused (at least the last 10).
d. User ids and passwords are "owned" by an individual and must not be
shared with others.
e. User accounts that have not been accessed (i.e. logged in to) for 30
days will be deactivated.
f. Inactive user accounts will be deleted after 14 days.

The numbers I have used are what I used in the corporate world for
systems that had no special security requirements (i.e. they did not
have any confidential data on them). What are other people doing for
this type of standard, if anything? Also, if you had your choice (not
subject to a committee agreeing), what would you choose for these items?


Please let me know if you have any questions.

Thanks,

Randy




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