Description

Security researchers have recently unearthed vulnerabilities in the embedded fingerprint sensors of popular laptop models like Dell Inspiron, Lenovo ThinkPad, and Microsoft Surface Pro X. These flaws allow for the bypass of Windows Hello fingerprint authentication. Blackwing Intelligence made these discoveries during their research supported by Microsoft's MORSE initiative, focusing on major embedded fingerprint sensor manufacturers such as ELAN, Synaptics, and Goodix. The fingerprint sensors scrutinized in the research were all Match-on-Chip (MoC) sensors, known for their microprocessors and secure storage for fingerprint matching. Despite their ability to prevent the replay of stored fingerprint data to the host, these sensors lack inherent protection against potential malicious sensor behavior, which might mimic genuine communication with the host. This could lead to false indications of successful user authentication or the replay of observed traffic. Even though Microsoft introduced the Secure Device Connection Protocol (SDCP) to mitigate vulnerabilities, researchers successfully bypassed Windows Hello authentication on the three laptop models using man-in-the-middle (MiTM) attacks. Employing a customized Linux-powered Raspberry Pi 4, they conducted software and hardware reverse-engineering. This process identified cryptographic weaknesses in the Synaptics sensor's custom TLS protocol, deciphered and re-implemented proprietary protocols, and exploited authentication process vulnerabilities. For Dell and Lenovo laptops, the authentication bypass involved identifying valid IDs and enrolling the attacker's fingerprint using a legitimate Windows user's ID. Vulnerability in the Synaptics sensor, utilizing a custom TLS stack instead of SDCP for securing USB communication, facilitated this attack. In the case of the Surface device equipped with an ELAN fingerprint sensor lacking SDCP protection and using unencrypted USB communication, the researchers successfully spoofed the fingerprint sensor after disconnecting the Type Cover containing the sensor. Additionally, the absence of SDCP on two out of three targeted laptops raised concerns. To address these vulnerabilities, Blackwing Intelligence emphasizes the importance for biometric authentication solution vendors to activate SDCP, highlighting its pivotal role in thwarting such attacks.