I helped someone cheat in an exam… and now they act like we’re close friends

This is such a weird situation. During an exam, someone sitting near me was struggling and asked for help. I didn’t think too much and just helped a bit. It was a one-time thing in my head. But after that, they started acting like we’re close. They keep talking to me, sitting next to me, messaging me… like we have some kind of bond now. And I don’t feel that way at all. I don’t even know them properly. Now I feel stuck because I don’t want to be rude, but I also don’t want to encourage something that I didn’t intend. And I definitely don’t want to get into a pattern of helping like that again. How do you handle this without making things awkward?