I consider myself internet savvy and @Twitter savvy but my @WhatsApp was hacked last night with the hacker sending messages to everyone in the address book asking for money.
Here is how it can happen to you.
A thread:

First I got followed on Twitter by a well known GI friend and I followed back. Didn’t realize I was already following him before and this was a fake account with the same profile details.

Next thing, I received a DM from him saying he is starting a WhatsApp group and would like me to join. I asked more details and the answer was a bit vague, for sharing information and experiences. Any how, I thought it must be for a research paper or for case discussions.

Then I said, here is my number, please add me to the Whatsapp group. Next, I received an odd a text message (looked like French?) and a link which I didn’t want to click on. So I sent a DM asking, can you please tell me how this works. He says, send me what you got!

Then, (stupidly), I sent him what I got on the text message. Obviously that has the verification code. Within seconds, my @WhatsApp logged out and I started getting strange phone calls from all international numbers.
Soon friends started texting and ringing with concern.

Basically, the messages start with, hi, how are you? If there is a reply, then, I need some help. If you reply again, then, I am trying to buy something on the internet but my card expired. Please send me a picture of the credit card.

The language is pretty poor with many errors and anyone who is alert will quickly know it is not from me. But I have had at least one person ring me and say that they have given the credit card number to the hacker. He is one of my smart friends, so it can happen to anyone.

Now, the only way I can stop this is if I can log back into my account and automatically log the other person out. But it is not easy. I am getting messages saying that there have been too many wrong attempts and I have to wait for several hour before trying again.

I have also sent an email off to @WhatsApp support to deactivate my number or do something. Meanwhile, I have posted on my Facebook and Twitter to alert as many of my friends. Please share as this can happen to anyone. I considered myself very internet savvy (no longer!).

Good news (sort of!). I have managed to log back into my account now, hopefully that should log out the hacker. All my messages are still there. I haven’t lost my address book.