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MS Employee Calls for No More Passwords
BobPaul writes "On his blog, Robert Hensing of the Microsoft PSS Security Team makes a really convincing argument for the abolishment of complicated passwords. He argues that precomputed hash tables, network sniffing, and programs like LoftCrack make passwords obsolete and dangerous in the windows environment. What does he recommend in their place? Passphrases: sentences and quotes that are easy to remember but may be more than 30 or 40 characters in length. With many companies requiring frequent password changes, (and we know exactly where that leads) this is a simple idea I'm surprised more people haven't been doing this more often."
What about biometrics? Passphrases are nothing more than longer passwords. I can see several things resulting from
converting to all passphrases. First, the person will probably use the same passphrase for everything because it's too difficult
to remember multiple passphrases. Second, it's difficult to remember passphrases! Phone numbers (In the US, at least) are limited to
10 digits because research shows the average person can only memorize 10 digits, as a result...we tend to write things down, or in the case of
data people are likely to store their passphrases in a central location that is still prone to theft/decryption.
Biometrics, on the other hand, requires that you only have your body present at the time! No special USB keys to lug around, no pieces of
paper with important passwords/phrases. This won't solve the problem of possible data interception when talking about remote
authentication--but every form of authentication is prone to such attacks when transmitted.
One thing I just read in my MCSE study book... Windows 2000 and up support 127-character passwords, but Windows NT, Windows 9x and Windows ME only support 14-characters in a password. A user who has a Windows password greater than 14 characters simply cannot using the older operating systems even if they otherwise should be able to.
Therefore, if you have any legacy systems to support, these password tips don't apply to you, and that's got to be part of the reason there hasn't been much of a movement to suggest that users use longer passwords.
One of the main obstacles to better security is that people are fundamentally lazy. Typing 30 or 40 characters is difficult to do, and it takes time, so people won't do it. Or if forced to do it, they will whine about it -- a lot.
I have convinced a majority of my friends & family to at least stop using dictionary words and names of pets. Instead, I have them pick some favorite line from a movie or book and then use the first letter of each word. It's easy to remember, so they don't stick it on the bottom of their keyboard. It also is not a word in the dictionary so at least Crack & friends can't be used to guess it.
For example, if one of my friends is a Dead Head, he might use "stlasom.oticbs" If you're a Dead Head you'll probably be able to guess the lyric. But you *won't* be able to find it in a dictionary.
Now replacing my brute force wordlists with "He's dead, Jim", "In soviet russia, passphrases validate YOU" and "passwords are for old korean people" will allow root access to 90% of the internet.
And I quote, "Open Sesame!"
When things get complex, multiply by the complex conjugate.
or
Make of that what you want, but:
Of course, I changed the password to something more politically correct before leaving the companies....
The right to offend is far more important than the right not to be offended. (Rowan Atkinson)
Lawrence Person (lawrencepersonh@gmailh.com (remove all "h"s to mail)
http://www.lawrenceperson.com/
1) it's just as easy (give or take the odd case where you're just able to sample a few bytes) to sniff a passphrase as a password
2) if most people's passphrases are made of dictionary words take from their active vocabularies, dictionary attacks are still very possible. If we figure a typical vocabulary of 25000 words and a six-word phase, hmmm, some quick math indicates we're in the range of a 14-character random alphanumeric+punctunation password -- not too bad. (Especially if you grant people bigger vocabularies....) But, suddenly, we're open to language-based attacks -- there's probably thesis project in here for someone to come up with good algorithms to narrow down the required attack dictionary.
Passphrases are just long passwords with (usually) low entropy. They still have the same problems... You have to have a separate passphrase for each account, and you have to trust the computer you're using not to log your keystrokes. I would much rather carry around a device that can authenticate me and never have to remember a password again.
Why don't we all just switch to USB tokens for authentication? You have one device that can authenticate you by generating an RSA signature without divulging any information that would allow someone else to pretend to be you. It amazes me that more people don't use these things. I've never used one, but have considered ordering one. Does anyone out there have experience with USB tokens? Is there a good model/brand to buy? Is it easy to get them to work with Linux and ssh? Do any brick-and-mortar stores sell them?
The company I work for has a password policy like this:
1. Must contain at least 8 characters
2. Must contain at least 2 lowercase letters
3. Must contain at least 2 capital letters
4. Must contain at least 2 numbers
Since a lot of people cant grok this we start to see passwords like 34erdfCV. If you are using a QWERTY keyboard take a look at that password and tell me whats wrong with it.
Since I saw this article in a MS Security newsletter I've started using passphrases. Here is an example of my Windows Server 2003 administrator login (local only, not going to help you). "Rent is due on the 5th". Now I see many comments already talking about how that is so much harder to type than "34erdfCV" but I beg to differ. For me at least it is much easier to type a coherent sentense than a bunch of random letters and numbers.
This password is not only easy to type, but it is very secure. I'm sure some mathematician is going to come down on my with a bunch of stats about how I'm wrong and what not but just the fact that the LM hash is not stored when you use a password larger than 14 characters helps significantly. Sure you can tell windows not to store a LM hash by editing the registry but do you really expect all employees of a mid size company to follow directions that start out like "Click Start, then Run. Type 'regedit' and click OK"?
Now of course this isn't going to defend you against the ol' linux bootdisk trick, or that awesome "NT Password Recovery" bootdisk, which is basically linux which allows you to overwrite the password, but thats what NTFS and encryption is for. And if you've got physical access all bets are off anyway. At least you know they wont be able to run a rainbow table lookup on your LM hash and figure it out in a few seconds.
Also, passphrases are easier to remember, harder to guess, harder to figure out by watching someone type them, and if your really that dense you can just pick up a book off your shelf, turn to a page, type in the first sentense and remember the book and page number.
And there is an added bonus to having a passphrase over 14 characters that you are all completely missing here. When the hot chick in accounting sees you keying in some enormously long password she will think your smart and savy and will want to have hot sex with you right there in the server room.
Well, maybe not the hot chick and sex part.
Now, what would be a good long slashdot post without a question for you to ponder. If you havent figured yet I'm the sysadmin at this company and am trying my hardest to find a way to "sell" this passphrase idea. It seems that the easiest thing to do in IT is configure complex servers and firewalls and support ID10T's. The hard part is "selling" common sense stuff like SSL and passphrases.
"You mean we're going to have to add an 's' to the end of 'http', do you really expect 100 people to change their bookmarks! They've been using those bookmarks all year!"
Insight from other admins very welcome.
Im dreaming ofa big bndwdth, That can resist the
subject - verb - object
(I like pizza).
Here's another:
adverb/adjective - object - verb
(Mean people suck).
The trick is finding the most common 3 word phrases (in English) and applying the basic grammatical rules you learned in school.
That guy didn't understand that passphrases/passwords are covered in cryptology under "authentication".
And any student of cryptology can tell you that PATTERNS are the problem.
With passphrases, there are too many GRAMMATICAL RULES and PATTERNS that make it simple to crack.
He focuses solely on the number of characters and never looks at how someone else would approach this to crack it.
Yep. I first learned about it in my forensics coursework.
...
For more information on this, this Google search produced some good sites explaining tihs.
Also, in just conducting that search, I learned that 2000 and XP is apparently immune from this particular problem, according to this site.
"With LM, password hashes were split into two separate 7-character hashes. This actually made passwords more vulnerable because a brute-force attack could be performed on each half of the password at the same time. So passwords that were 9 characters long were broken into one 7-character hash and one 2-character hash. Obviously, cracking a 2-character hash did not take long, and the 7-character portion could usually be cracked within hours. Often, the smaller portion could actually be used to assist in the cracking of the longer portion. Because of this, many security professionals determined that optimal password lengths were 7 or 14 characters, corresponding to the two 7-character hashes.
But things are different with newer versions of Windows. Windows 2000 and XP passwords can now be up to 127 characters in length and so 14 characters is no longer a limit. Furthermore, one little known fact discovered by Urity of SecurityFriday.com is that if a password is fifteen characters or longer, Windows does not even store the LanMan hash correctly. This actually protects you from brute-force attacks against the weak algorithm used in those hashes. If your password is 15 characters or longer, Windows stores the constant AAD3B435B51404EEAAD3B435B51404EE as your LM hash, which is equivalent to a null password. And since your password is obviously not null, attempts to crack that hash will fail.
With this in mind, going longer than 14 characters may be good advice. But if you want to enforce very long passwords using group policy or security templates, don't bother - neither will allow you to set a minimum password length greater than 14 characters."
*-*-*-*-*-*-*-*
"We are Linux. Resistance is measured in Ohms."
Microsoft calls for password replacement because of "precomputed hash tables"? This very amusing, because it is pretty much only Microsoft who is vulnerable to these attacks. Why? they store only the hash of the password. Because there is a (nearly) one-to-one correspondance between password and hash, attackers can build up tables of precomputed hashes and use these to directly look up the passwords.
Everybody else mixes random salt bytes into passwords prior to hashing. Unix was doing this over 20 years ago. Modern systems use long (16+ character) salts that make precomputed hash tables infeasible for many years to come.
Some platforms use a better system still, that makes it more difficult for password guessers now and well into the future.
The only intrinsic problem with passwords is that people choose dumb ones, but again this can easily be fixed with a little technology
I'm not sure why he was taking so many jabs at Linux. Well, okay... I know exactly why but this seemed especially odd to me since I have disallowed passwords on all my computers unless the user is sitting at the keyboard. And that is mainly because I haven't got X to work with one time passwords yet (besides... how would I calculate them without being able to run the program to generate one?).
I use s/key or opiekey (depending on OS) for ALL my remote logins. Both of these programs use a pass phrase but (even better) this pass phrase is never transmitted across the network... encrypted or not. What happens is the pass phrase is used to generate a one time pass phrase.
In practice it looks like this:
ssh localhost
otp-md5 498 la7365 ext
Password:
I then open another window: type in
opiekey 498 la7365 ext
Using the MD5 algorithm to compute response.
Reminder: Don't use opiekey from telnet or dial-in sessions.
Enter secret pass phrase:
type my passphrase at the prompt and it spits out:
GIG DIRE EGG HISS HUB COOK
I type that at the password prompt and go on my way (cut and paste between xterms is best here). Even if I was not using an encrypted protocol the password is useless once it is used. You can even hit enter once so the phrase will be echo'ed back to you on the screen so you don't mistype it. Doesn't matter if someone reads over your shoulder because GIG DIRE EGG HISS HUB COOK will never work again.
Next time my password might be:
KNEW LARD ARGO LARD BARE YOGA
Or whatever. The point is that it is a mixture of pass phrases with the ability to avoid sending your pass phrase over an untrusted connection. You can even print out a list of the next 10 pass phrases you will have so you can log in from a computer where you wouldn't trust it enough to run the opiekey program.
How exactly is this an insecure linux system, at least in regards to passwords?
lol, besides that... I think pass phrases are a good idea. Just a little anoying at first.
---
"Do not meddle in the affairs of sysadmins,
for they are subtle and quick to anger."
Gummi bears defeat fingerprint sensors
Using passphrases does not add much more entropy, although they may be easier to remember. They are still prone to sniffing, 40chars can easily be packed in a single ethernet frame. Could some one tell Microsoft to use encrypted connections?
Users hate passwords, they hate typing them, and they hate having to remember things. They will always opt for whatever is easy. They will hate you if you set a lower limit of 30 characters, and their passphrase was 28.
Passwords or passphrases - same thing - will be chosen easy the more obstacles you place on the users: Requiring users to change password every three months will leave your systems less secure:
Users will choose easier passwords, and/or they will rotate just two different passwords. No security gained.
Further, in the race with a bruteforce attack, nothing is gained unless you change your password to one that has been tried.
In stead, as the administrator you have a head start in the race with the crackers. Go password cracking and require users to change their password when it has been cracked.
If password is cracked too quickly it should be followed by disiplinary actions as a compromise of security. Ofcourse the users must be informed beforehand of such proceedures.
Just my 5euro-cent contribution...