MQTT and Friends - Introducing BrokerLine

When doing red team assessments, you come across all manner of technologies. Obscure cloud services crop up all the time, and something new always seems to be in play. A red team I did a number of years ago led me down another Azure rabbit hole, this time to the Publish/Subscribe (PubSub) service.For those unaware (which until I read about it, included me), Azure Web PubSub is a managed service that enables real-time communication between web applications and clients. It can be used for WebSocket comms and a range of other things.I've been on a bit of a C2 arc recently, looking at different avenues. Despite not being a fan of using C2 or depending on it for operations, I like to explore the "everything as a C2 channel" side quests now and again.PubSub is built on WebSocket technology and lets you add real-time features to your applications without managing the underlying infrastructure. I'm no stranger to WebSockets, having written about them in the past.Per Microsoft's description,…