For decades, the use of fingerprints to authenticate users to computers, networks, and restricted areas was (with a few notable exceptions) mostly limited to large and well-resourced organizations that used specialized and expensive equipment. That all changed in 2013 when Apple introduced TouchID. Within a few years, fingerprint-based validation became available to the masses as computer, phone, and lock manufacturers added sensors that gave users an alternative to passwords when unlocking the devices.
Although hackers managed to defeat TouchID with a fake fingerprint less than 48 hours after the technology was rolled out in the iPhone 5S, fingerprint-based authentication over the past few years has become much harder to defeat. Today, fingerprints are widely accepted as a safe alternative over passwords when unlocking devices in many, but not all, contexts.
A very high probability
A study published on Wednesday by Cisco’s Talos security group makes clear that the alternative isn’t suitable for everyone—namely those who may be targeted by nation-sponsored hackers or other skilled, well-financed, and determined attack groups. The researchers spent about $2,000 over several months testing fingerprint authentication offered by Apple, Microsoft, Samsung, Huawei, and three lock makers. The result: on average, fake fingerprints were able to bypass sensors at least once roughly 80 percent of the time.
The percentages are based on 20 attempts for each device with the best fake fingerprint the researchers were able to create. While Apple Apple products limit users to five attempts before asking for the PIN or password, the researchers subjected the devices to 20 attempts (that is, multiple groups of from one or more attempts). Of the 20 attempts, 17 were successful. Other products tested permitted significantly more or even an unlimited number of unsuccessful tries.
Tuesday’s report was quick to point out that the results required several months of painstaking work, with more than 50 fingerprint molds created before getting one to work. The study also noted that the demands of the attack—which involved obtaining a clean image of a target’s fingerprint and then getting physical access to the target’s device—meant that only the most determined and capable adversaries would succeed.
“Even so, this level of success rate means that we have a very high probability of unlocking any of the tested devices before it falls back into the PIN unlocking,” Talos researchers Paul Rascagneres and Vitor Ventura wrote. “The results show fingerprints are good enough to protect the average person’s privacy if they lose their phone. However, a person that is likely to be targeted by a well-funded and motivated actor should not use fingerprint authentication.”