India, March 7 -- The call came early in the morning on Thursday. A neighbour of over two and a half decades, now in her mid-70s, asking for help. Her phone, she said, had been hijacked. Someone had seized control of her WhatsApp account. She could see messages coming in, but couldn't reply. Even the housing society's WhatsApp group-normally an endless stream of messages about plumber visits and festival donations-had gone silent. The settings had been changed. No one could post. Only the hijacker could broadcast.

When she called, she was already in a rickshaw, on her way to the police station with a friend. But her voice carried panic of the kind that comes from realising your private space has been invaded. By the time I got there, a y...