"Hi! How are you?" is effectively a one word salutation, especially because people often respond with the same thing without answering the question. And when people do answer, they always say that they're doing well. That can't always be the case, but because it's in passing, I don't typically follow up on the specifics of what's actually going well.
But, if we're not actually interested in how someone is doing, we should just say, "Hi! Hope you're having a good day." It'd be a more genuine interaction.
I'm curious to run an experiment where I tell people I'm having a rough day when we're passing in the hallway. I wonder how many people would stop to talk about what's going on. Or is this phase so hardwired as a one word salutation that people won't be listening for a response?