What type of applications should be blocked to prevent sign-in attempts from less secure environments?

Blocking applications that rely on username/password authentication is essential for enhancing security in less secure environments. These applications often do not implement modern security protocols and might lack features such as two-factor authentication (2FA). As a result, they can be more vulnerable to unauthorized access and breaches, particularly in environments that do not have robust security measures in place.

By contrast, applications utilizing OAuth 2.0 for authentication are designed with better security practices in mind, as they allow users to authenticate without sharing their passwords directly with the application. This protocol helps in minimizing the risks associated with traditional username/password combinations.

Applications using app passwords for sign-in have a specific use case in secure environments where two-factor authentication might be in place. Blocking these can disrupt access for users who are otherwise operating in secure manners.

Focusing on applications installed from the Google Play Store is not a sufficient measure since the store can house apps that do not meet security standards, and installation from the store does not necessarily imply that the app follows good practices for user authentication. Therefore, the best practice is to block applications that rely on outdated username/password forms of authentication in less secure environments.