What is the WhatsApp scam where replying 'NO' can drain your bank account?

Hyderabad Police has warned of WhatsApp scam in which fraudsters send fake WhatsApp message saying, "Money has been debited from your account. If you didn't make this transaction, reply NO." When victims reply 'No' in panic, it triggers a malware attack allowing hackers to take control of phone and steal money. A CA lost lakhs of rupees in the scam.