The development of mobile applications that interact with common services in mobility environments such as Amazon Simple Storage Service (S3), Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS) or Amazon Mobile Analytics is becoming more frequent. To interact with these services, apps need to communicate with them and authenticate with some kind of credential (usually based on tokens). We have identified unsafe programming practices in the form of poor management of login credentials, which could allow an attacker to modify the behavior of the affected apps.