Security researchers from Tencent and Zhejiang University have unveiled a practical attack called “BrutePrint” that can bypass biometric fingerprint checks on Android smartphones. The attack, detailed in a research paper, is cost-effective and scalable, enabling unauthorized access to devices and authorization of payments.
Furthermore, by exploiting zero-day flaws and weak security in the fingerprint authentication framework and sensor implementation, the attack proceeds in four stages, allowing the attackers to steal stored fingerprint data and create a “fingerprint dictionary” for injection into the target device’s memory. While the attack was successful on Android devices, it failed on encrypted Apple models due to stronger protections.
BrutePrint overcomes rate limits and liveness detection, two common defenses in smartphone operating systems. The researchers found that the attack could bypass rate limits, granting them infinite attempts to succeed.
Additionally, to defeat liveness detection, they employed the Cycle Generative Adversarial Network (CycleGAN) technique, training a neural network to create dictionary images that appear genuine to smartphone safety checks. This approach allowed BrutePrint to succeed against Android devices approximately 71% of the time.
At the same time, the researchers emphasized that closing the vulnerabilities exploited by BrutePrint requires collaborative efforts between smartphone and fingerprint sensor manufacturers, as well as regular operating system updates.
As manufacturers have continually improved security measures, attackers have sought innovative ways to defeat fingerprint-based security checks. BrutePrint demonstrates the need for ongoing vigilance and the development of stronger countermeasures to ensure the effectiveness of biometric authentication systems.
