Frequent password changes are useless

“Memorizing a lot of passwords… is a horrifying experience… is it petronas@70… or petronas@71?… geez!” –MKK-

Tue Apr 13, 2:16 pm ET

Users hate them. They're a massive headache to network administrators. But IT departments often mandate them nonetheless: regularly scheduled password changes — part of a policy intended to increase computer security.

Now new research proves what you've probably suspected ever since your first pop-up announcing that your password has expired and you need to create a new one. This presumed security measure is little more than a big waste of time, the Boston Globe reports.

Microsoft undertook the study to gauge how effectively frequent password changes thwart cyber attacks, and found that the advice generally doesn't make much sense, since, as the study notes, someone who obtains your password will use it immediately, not sit on it for weeks until you have a chance to change it. "That’s about as likely as a crook lifting a house key and then waiting until the lock is changed before sticking it in the door," the Globe says.
On the bright side, changing your password isn't harmful, either, unless you use overly short or obvious passwords or you're sloppy about how you remember them. (Many users forced to change their password too frequently resort to writing them on sticky notes attached to their monitor, about the worst possible computer security behavior you can undertake.)

Rather, frequent password changes are simply a waste of time and, therefore, money. According to the Microsoft researcher's very rough calculations: To be economically justifiable, each minute per day that computer users spend on changing passwords (or on any security measure) should yield $16 billion in annual savings from averted harm. No one can cite a real statistic on password changes' averted losses, but few would estimate it's anywhere approaching $16 billion a year.

Bottom line, IT departments: Drop the password-change mandates. You're only creating extra work for yourselves and making the rest of us hate you.