Re: Strong Passwords Revisited

From: Lohkee (Lohkee@worldnet.att.net)
Date: 01/21/03

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    From: "Lohkee" <Lohkee@worldnet.att.net>
    Date: Tue, 21 Jan 2003 02:07:22 GMT
    
    

    "John Elsbury" <johne@snospam.sovereign.co.nz> wrote in message
    news:3e2ca05f.362775543@news.clear.net.nz...
    > On Sun, 19 Jan 2003 21:04:59 GMT, "Lohkee" <Lohkee@worldnet.att.net>
    > wrote:
    >
    > <snip>
    >
    > >On one hand we have an "attacker" who is literally handed the
    > >password file which he then runs against a password cracker on a
    dedicated
    > >system at extremely high speeds (essentially an unlimited number of
    attempts
    > >to identify a given password), on the other hand we have an attacker who
    > >must first somehow penetrate your system and successfully capture the
    > >password file (all without ever being detected and stopped - in which
    case
    > >you have a far more serious problem on your hands than weak passwords)
    > >before he can even begin to think about cracking those passwords!
    Attempting
    > >to equate these two vastly different scenarios is absurd. Think about it
    for
    > >a moment; hackers would have had free rein on almost every system
    > >imaginable for the past twenty years if the results typically obtained by
    > >password crackers were representative of anything even remotely close to
    > >reality.
    > >
    > I think that says it all. A password is one of a set of control
    > measures, and has to be seen in that context. Other control measures
    > in the set include:
    >
    > Not making the password file (even encrypted) available to anybody
    > other than those with a genuine need;
    > Not allowing users to reuse passwords;
    > Forcing periodic password expiry;
    > Blocking / disbaling login accounts after a (small) set number of
    > failed access attempts;
    > Logging and auditing exception conditions (such as failed password
    > attempts).
    >
    > There is a convenience / security formula which will include factors
    > like:
    > * Password length and composition rules (to avoid trivial passwords)
    > -vs - probability that a user will have trouble remembering them;
    > * Number of attempts before account gets locked -vs - probability that
    > legitimate users will get locked out (or have their access denied by
    > mischievous persons) - vs - probability that a wild guess will
    > succeed;
    > * Cost/Number of Help Desk calls arising from forgotten passwords -vs
    > - incidence of forgotten passwords (tokens like SecurID sell based on
    > this margin)
    > Frequency and quality of exception audit and follow-up activity.
    >
    > <snip>

    All of which can be measured and evaluated mathematically. Security through
    science or security through superstition. To me, it's a no-brainier
    (although I do admit seem to being in a very, very small minority - welcome
    to the club john)!

    Lohkee!