Social Media sites such as Facebook and twitter encourage you to enable “apps” that work their platforms, often demanding privileges to generate messages on your behalf. The typical scenario is that you use them only once or twice and forget about them.
It is the fastest growing attack vector into Microsoft office 365 – something that Microsoft is moving to stop but it is taking time.
It is always good to go through you accounts and disable the apps. Be ruthless – you probably weren’t using them anyway and if you do need them – they are a few clicks to re enable. Here’s a complete guide for all services to check: