A wide range of mobile applications for the Android operating system require users to input sensitive data, such as PINs or passwords. Given the ubiquitous and security-critical role of credentials, it is paramount that programs process secrets responsibly and do not expose them to unrelated parties. Unfortunately, users have no insight into what happens with their data after entrusting it to an application. In this paper, we introduce a new approach to identify and follow the trace of user input right from the point where it enters an application. By using a combination of static slicing in forward and backward direction, we are able to reveal potential data leaks and can pinpoint their origin. To evaluate the applicability of our solution, we conducted a manual and automated inspection of security-related Android applications that process user-entered secrets. We find that 182 out of 509 (36%) applications insecurely store given credentials in files or pass them to a log output.