Improper Authentication in SHAREit for Android - CVE-2019-9939

Detailed vulnerability description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to the application grants access permissions to any client that requests a non-existing page. A remote attacker can send HTTP GET request to the application to port 2999/tcp, request a non-existing page. The application will add the attacker's device into the list of recognized devices and subsequent requests to the application will be considered as authenticated requests.

A remote attacker with ability to directly connect to the application via network is able to bypass authentication and gain unauthorized access to files on the device.

How to mitigate CVE-2019-9939

Sources

• https://blog.redforce.io/shareit-vulnerabilities-enable-unrestricted-access-to-adjacent-devices-files/
• https://github.com/redforcesec/DUMPit/