Entries Tagged "PINs"

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Is iPhone Security Really this Good?

Simson Garfinkel writes that the iPhone has such good security that the police can’t use it for forensics anymore:

Technologies the company has adopted protect Apple customers’ content so well that in many situations it’s impossible for law enforcement to perform forensic examinations of devices seized from criminals. Most significant is the increasing use of encryption, which is beginning to cause problems for law enforcement agencies when they encounter systems with encrypted drives.

“I can tell you from the Department of Justice perspective, if that drive is encrypted, you’re done,” Ovie Carroll, director of the cyber-crime lab at the Computer Crime and Intellectual Property Section in the Department of Justice, said during his keynote address at the DFRWS computer forensics conference in Washington, D.C., last Monday. “When conducting criminal investigations, if you pull the power on a drive that is whole-disk encrypted you have lost any chance of recovering that data.”

Yes, I believe that full-disk encryption—whether Apple’s FileVault or Microsoft’s BitLocker (I don’t know what the iOS system is called)—is good; but its security is only as good as the user is at choosing a good password.

The iPhone always supported a PIN lock, but the PIN wasn’t a deterrent to a serious attacker until the iPhone 3GS. Because those early phones didn’t use their hardware to perform encryption, a skilled investigator could hack into the phone, dump its flash memory, and directly access the phone’s address book, e-mail messages, and other information. But now, with Apple’s more sophisticated approach to encryption, investigators who want to examine data on a phone have to try every possible PIN. Examiners perform these so-called brute-force attacks with special software, because the iPhone can be programmed to wipe itself if the wrong PIN is provided more than 10 times in a row. This software must be run on the iPhone itself, limiting the guessing speed to 80 milliseconds per PIN. Trying all four-digit PINs therefore requires no more than 800 seconds, a little more than 13 minutes. However, if the user chooses a six-digit PIN, the maximum time required would be 22 hours; a nine-digit PIN would require 2.5 years, and a 10-digit pin would take 25 years. That’s good enough for most corporate secrets—and probably good enough for most criminals as well.

Leaving aside the user practice questions—my guess is that very few users, even those with something to hide, use a ten-digit PIN—could this possibly be true? In the introduction to Applied Cryptography, almost 20 years ago, I wrote: “There are two kinds of cryptography in this world: cryptography that will stop your kid sister from reading your files, and cryptography that will stop major governments from reading your files.”

Since then, I’ve learned two things: 1) there are a lot of gradients to kid sister cryptography, and 2) major government cryptography is very hard to get right. It’s not the cryptography; it’s everything around the cryptography. I said as much in the preface to Secrets and Lies in 2000:

Cryptography is a branch of mathematics. And like all mathematics, it involves numbers, equations, and logic. Security, palpable security that you or I might find useful in our lives, involves people: things people know, relationships between people, people and how they relate to machines. Digital security involves computers: complex, unstable, buggy computers.

Mathematics is perfect; reality is subjective. Mathematics is defined; computers are ornery. Mathematics is logical; people are erratic, capricious, and barely comprehensible.

If, in fact, we’ve finally achieved something resembling this level of security for our computers and handheld computing devices, this is something to celebrate.

But I’m skeptical.

Another article.

Slashdot has a thread on the article.

EDITED TO ADD: More analysis. And Elcomsoft can crack iPhones.

Posted on August 21, 2012 at 1:42 PM • View Comments

Attack Against Point-of-Sale Terminal

Clever attack:

When you pay a restaurant bill at your table using a point-of-sale machine, are you sure it’s legit? In the past three months, Toronto and Peel police have discovered many that aren’t.

In what is the latest financial fraud, crooks are using distraction techniques to replace merchants’ machines with their own, police say. At the end of the day, they create another distraction to pull the switch again.

Using information inputted by customers, including PIN data, the criminals are reproducing credit cards at an alarming rate.

Presumably these hacked point-of-sale terminals look and function normally, and additionally save a copy of the credit card information.

Note that this attack works despite any customer-focused security, like chip-and-pin systems.

Posted on June 19, 2012 at 1:02 PM • View Comments

"1234" and Birthdays Are the Most Common PINs

Research paper: “A birthday present every eleven wallets? The security of customer-chosen banking PINs,” by Joseph Bonneau, Sören Preibusch, and Ross Anderson:

Abstract: We provide the first published estimates of the difficulty of guessing a human-chosen 4-digit PIN. We begin with two large sets of 4-digit sequences chosen outside banking for online passwords and smartphone unlock-codes. We use a regression model to identify a small number of dominant factors influencing user choice. Using this model and a survey of over 1,100 banking customers, we estimate the distribution of banking PINs as well as the frequency of security-relevant behaviour such as sharing and reusing PINs. We find that guessing PINs based on the victims’ birthday, which nearly all users carry documentation of, will enable a competent thief to gain use of an ATM card once for every 11-18 stolen wallets, depending on whether banks prohibit weak PINs such as 1234. The lesson for cardholders is to never use one’s date of birth as a PIN. The lesson for card-issuing banks is to implement a denied PIN list, which several large banks still fail to do. However, blacklists cannot effectively mitigate guessing given a known birth date, suggesting banks should move away from customer-chosen banking PINs in the long term.

Blog post.

EDITED TO ADD (2/22): News article

Posted on February 21, 2012 at 7:36 AM • View Comments

Improving the Security of Four-Digit PINs on Cell Phones

The author of this article notices that it’s often easy to guess a cell phone PIN because of smudge marks on the screen. Those smudge marks indicate the four PIN digits, so an attacker knows that the PIN is one of 24 possible permutations of those digits.

Then he points out that if your PIN has only three different digits—1231, for example—the PIN can be one of 36 different possibilities.

So it’s more security, although not much more secure.

Posted on January 6, 2012 at 6:30 AM • View Comments

Stealing ATM PINs with a Thermal Camera

It’s easy:

Researchers from UCSD pointed thermal cameras towards plastic ATM PIN pads and metal ATM PIN pads to test how effective they were at stealing PIN numbers. The thermal cams didn’t work against metal pads but on plastic pads the success rate of detecting all the digits was 80% after 10 seconds and 60% after 45 seconds. If you think about your average ATM trip, that’s a pretty wide window and an embarrassingly high success rate for thieves to take advantage of.

Paper here. More articles.

Posted on August 24, 2011 at 7:13 AM • View Comments

Man-in-the-Middle Attack Against Chip and PIN

Nice attack against the EMV—Eurocard Mastercard Visa—the “chip and PIN” credit card payment system. The attack allows a criminal to use a stolen card without knowing the PIN.

The flaw is that when you put a card into a terminal, a negotiation takes place about how the cardholder should be authenticated: using a PIN, using a signature or not at all. This particular subprotocol is not authenticated, so you can trick the card into thinking it’s doing a chip-and-signature transaction while the terminal thinks it’s chip-and-PIN. The upshot is that you can buy stuff using a stolen card and a PIN of 0000 (or anything you want). We did so, on camera, using various journalists’ cards. The transactions went through fine and the receipts say “Verified by PIN”.

[…]

So what went wrong? In essence, there is a gaping hole in the specifications which together create the “Chip and PIN” system. These specs consist of the EMV protocol framework, the card scheme individual rules (Visa, MasterCard standards), the national payment association rules (UK Payments Association aka APACS, in the UK), and documents produced by each individual issuer describing their own customisations of the scheme. Each spec defines security criteria, tweaks options and sets rules—but none take responsibility for listing what back-end checks are needed. As a result, hundreds of issuers independently get it wrong, and gain false assurance that all bases are covered from the common specifications. The EMV specification stack is broken, and needs fixing.

Read Ross Anderson’s entire blog post for both details and context. Here’s the paper, the press release, and a FAQ. And one news article.

This is big. There are about a gazillion of these in circulation.

EDITED TO ADD (2/12): BBC video of the attack in action.

Posted on February 11, 2010 at 4:18 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.