An issue was discovered on OnePlus 7 Pro devices before 10.0.3.GM21BA. The firmware was found to contain functionality that allows a privileged user (root) in the Rich Execution Environment (REE) to obtain bitmap images from the fingerprint sensor because of Leftover Debug Code. The issue is that the Trusted Application (TA) supports an extended number of commands beyond what is needed to implement a fingerprint authentication system compatible with Android. An attacker who is in the position to send commands to the TA (for example, the root user) is able to send a sequence of these commands that will result in the TA sending a raw fingerprint image to the REE. This means that the Trusted Execution Environment (TEE) no longer protects identifiable fingerprint data from the REE.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-7958
• https://www.synopsys.com/blogs/software-security/cve-2020-7958/