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Please Do Not Change Your Password
cxbrx writes "Mark Pothier's Boston Globe article, 'Please do not change your password,' covers a paper by Microsoft Researcher Cormac Herley, 'So Long, and No Thanks for the Externalities: the Rational Rejection of Security Advice by Users,' from the 2009 New Security Paradigms Workshop. Herley argues 'that user's rejection of the security advice they receive is entirely rational from an economic perspective.' Herley discusses 'password rules,' 'teaching users to recognize phishing sites by reading URLs,' and 'certificate errors.' Users obviously choose bad passwords, but does password aging actually help? There was some discussion on TechRepublic. I'm especially interested in hearing about studies about password aging."
hunter2
We have a password expiration policy at my work. Every time I change my password I have to memorize a new one. So I pick a password that's easy to remember, as such it's also easy to guess. If I could just memorize a password once, and keep it forever I'd be using a password that's essentially random. This policy is nonsense.
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"Change your passwords and be rooted." -- JIRA attackers.
1. Apache Foundation Attacked, Passwords Stolen
2. Please Do Not Change Your Password
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Password aging is one of those policies that sounds like it makes some degree of sense only if you don't have any understanding of human nature.
Here in reality, forcing people to change their password every 30 or 60 or 90 days only has a few possible results:
(1) A lot more people writing down passwords and sticking them to their monitors. Who the hell can remember a new eight-digit string of nonsense every month?
(2) A lot more easy-to-guess passwords
(3) Incremented passwords (FuckTheSecurityGuys14)
This is why I consider password policies a great indicator of where your IT department is on the "keepin' it real" scale: No restrictions, you IT people are idiots and don't care or understand security. Reasonable restrictions (min 8 characters, letters and numbers) and you're in the sweet spot. Passwords that expire every 15 minutes, your IT people are idiots and don't care or understand security.
Every year during my review, I just pray the words "slashdot.org" aren't mentioned.
Password aging is not only irritating for users, it causes them to choose even worse passwords, or to write their passwords down. If you are lucky, and they do neither of these, then it is very likely that they will use "strong-password-1", "strong-password-2".
Enjoy life! This is not a dress rehearsal.
There is one thing worse than a bad password, and that is one that needs to be written down on a post-it note.
I see password security as an exponential curve, on a graph, reaching a certain peak and then dropping to zero. That dropping point is where the password rules become so complicated that most people would rather write the password down than try to remember it. That piece of paper suddenly became your weak point in the security model. For this reason you password policies need to focus on something that is sufficiently secure, but not so secure that it is in effect insecure.
Jumpstart the tartan drive.
And this points to a huge problem in IT departments, companies in general and our whole society. So much effort needs to be put into CYA activities, not because you're not doing your job right, but because you are liable to be subject to the whimsical judgement of stupid or ignorant people. Appearing to do the right thing is perceived as much more important that actually doing the right thing because failures of appearance tend to have much worse consequences. Look at Congress, 90% of what they do is so they appear to taking positive action on some issue, regardless of the effects it will have. And for them, it clearly works because they keep getting re-elected despite being the most consistently incompetent group of people drawing a salary in the U.S..
You are in a maze of twisty little passages, all alike.
How many times have you seen "the password must be between x and y characters in length and must contain blah blah"?
I want to enter a full sentence. Like "this is my password and you won't be able to guess it, you idiot". You aren't making this possible, because you're thinking like geek programmers who use randomly-generated strings of 8-12 characters by the dozens.
I write code and do inter-office support for my apps. Do you know how many times someone told me "I forgotz my password, halp!!11" after they were instructed to use a full sentence with a minimum of twenty-five characters? Zero. Nobody ever forgot it.
Password: Aaaaaayyy
The biggest problem with password security is user education.
USER. EDUCATION.
Forget the WHY password complexity and expiring passwords is important; end-users don't care about that.
Educate end-users on how to make passwords that are complex and easy to remember. Such a thing IS possible. For example teach users to pick a phrase or sentence and type that in, replacing all the instances of the letter E with the number 3 and to capitalize all vowels. All the user needs to remember is the phrase and the rules to make it complex. And the phrase can be something VERY easy to remember like "my daughter was born in march" which turns into "mydAught3rwAsbOrnInmArch". Maybe you leave the spaces in. Maybe you change A to 4 or L to 1. Whatever the user wants.
It produces a complex, easy to remember password.
Pretend it would take about two months of processing time for a computer or cluster of computers to crack your 16 character length password with symbols, uppercase, lowercase and numbers. Now imagine that if your password were to be changed every month that the two month duration attempt to crack the password is useless since the password has changed and another two month attempt would have to be initiated.
That is an incorrect argument made by somebody who knows nothing about statistics.
First, if the time taken to crack a password is two months, and you change your passwords every two months, then there's a 50% chance of cracking the password in the first attempt, and a 100% chance of cracking the password the second attempt. So your example doesn't work.
Now, suppose a cracker has a, say 1% chance of guessing a password per month of attempts, and is attacking, say, 10,000 accounts. On the average, the cracker will have a ten hits every month, but he will only break your account, on the average, once every 8 years. Still, that's a 12 percent chance of you getting compromised in a year, and a 6 percent chance you'll get hit in six months. So, can you reduce that 6 percent chance by changing your password every 2 months? NO. The chance that your change password moves into the window of passwords that the cracker is going to try next month is exactly equal to the chance that the password change moves the password out of the window the cracker is trying. The odds of the cracking succeeding does not change at all by password changing.
The number of passwords that the cracker guesses per month does not change.
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As a long time sysadmin, my experience has been, the more onerous the password aging algorithm, the more likely that passwords will be on yellow stickies under the keyboard.
For instance, if your password expires monthly and you're required to pick a password with upper case, lower case, numbers and symbols, I guarantee that the majority of your users will write it down and stick it to something easily accessible.
If you get really draconian about keeping passwords on stickies on the monitor or under the keyboard, they'll keep it in their pocketbook or stuck to the back of their cell phone, which is difficult to track and actually a worse security hole (because the building at least has physical security).
My opinion is that password aging and password complexity rules are a managerial line item, not really a security strategy. A true security strategy is a combination of good logging, regular analysis, and tools like password breakers.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.