Do white tip reefs shark attack humans?

Yes, it has been known. Very rare though - key things to think about : Don't look like a fish - if you have very white bits on your body (palms, soles of feet) stay out until you have a tan. Some attacks on people are known but many are apocryphal and who knows what type of shark it was? Statistically you more likely to be struck by lightning or killed by a horse. Similarly if you doing Scuba stuff, be aware that metal buckles on your kit will flash off the sunshine and look like the side of a fish.