Cheers.
The message was sent to a good number of people on their contact's list, presumably everyone on the list.
To do that, would seem somebody has been in the account?
Yes, that sounds right.
Bet thing to do is to change the account password immediately and setup the two-step verification.
It's just weird.
The message was "you have a knew what's app message, click here to view it".
Thanks for posting the link Kinboshi, i'll let them know and that should sort it.
The link probably tries to install some malware/virus on the person's computer. Most people won't click or install anything, but they only need one or two to do so, and it can be quite lucrative for them.