It’s Easy to Bypass Smartphone Fingerprint Security

Ever since Apple delivered an iPhone with Touch ID there have been all kinds of ways to defeat the fingerprint sensor. There have been some elaborate (and expensive) methods from using 3-D printing to using Gummi Bears and everything in between. Back in September of 2013, German hacker Starbug successfully proved that bypassing Touch ID was “no challenge at all,” according to Ars Technica. As Starbug mentioned in the interview, it took him nearly 30 hours from unpacking the iPhone to developing the hack to reliably bypass the fingerprint security.

At the recent 31C3 conference, the folks from Chaos Computer Club demonstrated how easy it was to grab the German Defense Minister’s (Ursula von der Leyen) fingerprint through press photos. The photos were taken using only a regular camera. They then used off-the-shelf software (VeriFinger) to take that fingerprint and make an image that ready for printing. It may take some planning to lift someone’s fingerprint, but Starbug contends that there are many likely candidates right on the smartphone screen itself and the casing.

An even lower tech attack is to lift the actual finger of the user. Harrison Green, the 7-year-old son of Johns Hopkins University professor Matthew Green did just that. He snuck into his father’s room while he was sleeping and pressed his dad’s fingerprint on the sensor. No faking or printing required. No software needed, but his attack works one hundred percent of the time. You can’t have a better success rate than that. The best part of the story is that professor Green teaches computer security and cryptology.

It’s not just Apple. The Samsung Galaxy S5 has a fingerprint sensor too. So does the HTC One Max. As the cost of the sensors keeps coming down, expect to see more and more smartphones equipped with them. Just because your smartphone has a fingerprint sensor doesn’t mean that you should use it. Sure it’s convenient, but it’s not very secure as we’ve already indicated in the examples.

Since it may take a lot of planning to lift a sample of your fingerprint, most people would think it is a pretty safe way to secure your smartphone. You might agree, but we wouldn’t recommend it. In fact, we wouldn’t recommend using any biometrics to secure a device. Once your fingerprint, retina, DNA or other biological data is compromised (more correctly the electronic representation of the biometric data) you’re toast. In all likelihood, you are not going to replace your fingertips or get an eyeball transplant.

Other than the security issue, there’s another reason NOT to use a fingerprint to secure your smartphone. In October, A Virginia Circuit Court Judge has ruled that you can be compelled to give up your fingerprint to unlock your device. Not so with a PIN. A PIN is considered “knowledge” and not something physical. So don’t spend that extra money just to get a fingerprint sensor that you probably shouldn’t be using in the first place.

The authors are the President and Vice President of Sensei Enterprises, Inc., a legal technology, information security and digital forensics firm based in Fairfax, VA. 703-359-0700 (phone)


  1. If security is treated as a priority, it would be fairly trivial to allow the combination or two or more security features. Some combinations might not impact useability in any significant degree:

    Fingerprint plus password could be implemented in current versions with a software upgrade.

    Fingerprints plus voice password would probably be easy to hack if specifically targeted, but would provide strong security against random theft/lost phones etc., be easy to implement, and convenient for users in most situations.

    Fingerprint plus password plus where and how hard you press and the way you swipe the home screen away may require new sensors, but would be doable and hard to duplicate (possible with video of the opening, but video is harder to come by than photos, and the operator’s hand would obscure the relevant activities from most angles.)

  2. As a person who spent a career in computer hardware design including a stint in communications & security, I am floored by the widespread acceptance of biometrics for many of the same reasons you state. Today’s “secure” is tomorrow’s “toy”. Cutting edge today is the playground for tomorrow’s script kiddies. Using biometric password technology is nothing less than using a weak password that can’t be changed. It’s very Hollywood, and that probably explains its wide acceptance, but keep in mind that Britney Spears, Paris Hilton & Kim Kardashian have also enjoyed wide acceptance. Biometrics are the Kardashians of the security world.

    Want to make something really secure? Make it dual challenge with one metric having to do with the hardware and one having to do with the user. For instance, the user has a password and the device must be in one of a specific set of locations. Or make time part of the equation. Banks have been doing this for decades. If you cant guard the unlocking of something 24/7, then don’t make it unlockable 24/7. This is not rocket science. The basic tenets of computer security have been poked and prodded for half a century now. The nature of security is deeply understood and the folly of biometrics has been patently obvious for decades. But because Hollywood has made it seem glamorous and Apple uses glamor to sell technology, this turd of a security technology is becoming common despite every engineer with a computer security background simultaneously facepalming.