The system must obfuscate the data if the application is not in focus.
CWE-200: Exposure of Sensitive Information to an Unauthorized Actor: The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
CWE-359: Exposure of Private Personal Information to an Unauthorized Actor: The product does not properly prevent a person's private, personal information from being accessed by actors who either are not explicitly authorized to access the information or do not have the implicit consent of the person about whom the information is collected.
GDPR. Art. 5: Principles relating to processing of personal data.(1)(f): Personal data shall be processed in a manner that ensures appropriate security of the personal data, including protection against unauthorized or unlawful processing and against accidental loss, destruction or damage.
ISO 27001:2013. Annex A - 18.1.3: Protect records against loss, destruction, forgery, unauthorized access and unauthorized release, in accordance with legal, regulatory, contractual and business requirements.
OWASP Top 10 A3:2017-Sensitive Data Exposure: Many web applications and APIs do not properly protect sensitive data, such as financial, healthcare and PII. Attackers may steal or modify such weakly protected data to conduct credit card fraud, identity theft or other crimes. Sensitive data may be compromised without extra protection, such as encryption at rest or in transit, and requires special precautions when exchanged with the browser.
OWASP-ASVS v4.0.1 V8.3 Sensitive Private Data.(8.3.4): Verify that all sensitive data created and processed by the application has been identified, and ensure that a policy is in place on how to deal with sensitive data.