Voluntary Disclosure Is the Threat to Password Security

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By Rob Pegoraro
Sunday, June 12, 2005

Computers can remember complex bits of data effortlessly, but people routinely fumble that task. Naturally, one of the big trends in computing security is making users memorize complex passwords -- then regularly wipe those from their memory in favor of equally obscure replacements.

To judge from the stern advice handed out by banks, Internet providers and information technology departments -- often, I suspect, after prodding by accounting departments and liability lawyers who don't want to be blamed for a security breach -- computer security hinges almost entirely on you choosing a string of letters, numbers and symbols in an order that has no correlation to any word or phrase that has ever been spoken or written in English or any other language.

That's fiction. First, while avoiding obvious passwords still constitutes a common-sense defense, that won't stop most password theft attempts these days. Second, forcing people to choose the most obscure passwords possible, then choose new ones every few months, is more likely to grease the skids for a successful compromise of those users' accounts.

This is because passwords aren't stolen in ways you might expect; a bad guy doesn't sit down in front of your computer and start typing in guess after guess until he succeeds. In the real world, accounts are usually cracked in two ways -- only one of which can be slowed or stopped by the use of a sufficiently inscrutable password.

One is to get access to the computer that stores users' login info. If the master password file stored on that machine is encrypted -- it should be, but sometimes is not -- the attacker then runs a password-cracking program to break that encoding. Otherwise, he or she can read the file as-is.

The other method relies on someone surrendering a password voluntarily. For example, an attacker can hide a program on a victim's computer to record each tap of the keyboard -- often by exploiting an old, long-since-patched vulnerability in Windows or by hiding the "keystroke logger" in a tempting download.

Or the attacker can just ask nicely for the password -- what's called "social engineering." The victims can be technical staff at a bank or an Internet provider who get a call from somebody claiming to be a colleague elsewhere in the company. Or the victims can be individual users who receive "phishing" e-mails imploring them to verify their account information by clicking on a link to a phony Web site done up to appear like that of a trusted institution.

The quality of a password matters only against the first type of attack -- the brute-force, code-breaking assault, which will hit pay dirt more quickly if stored passwords appear in dictionaries.

That's why security experts tell password creators to avoid using real words or names, even when altered by substituting letters with similar-looking numbers or symbols (for example, replacing "i" with "!" or "1"). One common suggestion is to use words only as ingredients -- say, by combining the first letters of names of friends or titles of favorite books.

But if an attacker employs keystroke logging or social engineering, it doesn't matter whether your password is "password" or "92nkkcx-j1!" Even the most inscrutable login offers no defense against those tactics -- which are what most attackers seem to employ these days.

"If you go back 10 years ago, password cracking was the way to do things," said Marty Lindner, a senior member of the technical staff at the CERT Coordination Center, the network-security center founded at Carnegie Mellon University in 1988. Now, however, he said that phishing and other social engineering attacks are "far more prevalent, far more devastating than anything else."

Granted, getting actual numbers on how people's accounts were broken into is difficult -- few institutions want to discuss how some teenage hacker managed to own them. But there's no arguing that phishing and spyware attacks are only getting worse, and understandably so; why should an Internet con artist waste time mastering password-cracking routines when there are smoother roads into the bank vault?


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