This means that if you’re the type of person who reuses their passwords, hackers could potentially get into your accounts. To better safeguard its users on its desktop and web app, WhatsApp appears to be testing out a two-step verification system for the desktop and web version of its service.
This means that whenever you register your WhatsApp account, in addition to the PIN that is sent to your phone as a one-time password, you’ll also have to enter a personal PIN to verify that it is indeed you who is trying to access the account. This is meant to help fight against potential SIM swap attacks where a person has somehow cloned your SIM or stolen your SIM.
So even if they receive the one-time PIN, as long as they do not know your personal PIN, they won’t be able to access your WhatsApp account. This feature appears to be in testing so it isn’t available to everyone yet, so don’t be alarmed if you don’t see this option available for you.