This detection rule focuses on identifying when custom applications are permitted in Microsoft Teams, as this capability can be exploited by adversaries to establish persistent access within an organization. The rule specifically monitors changes in tenant settings that allow for the interaction of custom applications. If an organization utilizes custom apps beyond what is available in the Teams app store, these can be developed and uploaded, potentially leading to unauthorized access if misused. The detection demonstrates organizational awareness of risks associated with enabling such functionalities. The rule alerts upon the successful enabling of `Allow sideloading and interaction of custom apps` in O365 settings, highlighting the need for vigilance around configuration changes that could indicate compromise. Investigation steps include reviewing audit logs, verifying user identities, and ensuring that recently uploaded applications are legitimate. Possible false positives include routine administrative changes, which can be filtered through exceptions, and specific scheduled maintenance activities. The rule's response and remediation procedures emphasize disabling the custom application interaction setting if unauthorized changes are detected, conducting thorough reviews, and implementing stronger policies regarding custom applications.