Bobby Monks was in her kitchen cooking dinner when the message came in over WhatsApp. Chicken was sizzling on the stove. Her son had just walked in the door. Her dogs were barking. She wasn’t wearing her reading glasses.

In this brief moment of domestic chaos, she clicked on a link that was supposedly going to help a friend activate his Instagram account. Instead, her own account got hacked. “This all went down in less than one minute,” Ms. Monks said. “I was like, ‘What the hell just happened?’”