Mobile application security testing is crucial to protect users' data and prevent potential breaches. It involves identifying vulnerabilities in the app's software that may cause data loss or unauthorized access. The challenges of mobile application security testing include integrations with other apps, unsecured communications, security breaches that allow malware installation, utilization of different authentication procedures, test hidden parts of the application, and security requirements when building a mobile app. To overcome these challenges, it is essential to follow six security requirements: confidentiality, integrity, authentication, authorization, availability, and non-repudiation. By prioritizing security testing and following these guidelines, developers can reduce risk and create more secure mobile apps that protect user data.