Cases of hackers hijacking high ranking accounts and then using them to post malware are quite common this days. The hackers nolonger change the passwords or emails as they know that they will be locked out and won't be able to use your account to post their malicious links.

What they do, they just keep logging in and posting when you don't know and before you realise it, you account is already flagged for sharing malware and even banned.

Mine got hacked too but the cause was using the same log in credentials on different sites. One site's security was breached and the passwords got leaked.