Despite removing all the viruses manually, it appears that their hosting account has been compromised by hackers despite the support's continuous denial.
But they do confessed outsourcing their direct customer service and website security to 3rd party SiteLock in my live online chat with their rep since their email service has been discontinued.
Some of you guys might disagree with me but I still want to say.
Do Not Sign Up For Hostgator.
Their current support and services are no longer the same as before say 4-5 years ago.
Because when you do, they try to refer you to /upsell you SiteLock security services and if you don't, they will continuously send you reports like this of your sites disabled due to malware attack.
In my 5 years as customer, I have never encountered this until mid Nov.
Even if you do signed up with SiteLock, there is NO guarantee that your problem will be solved permanently.
SiteLock will continue to upsell you via email or phone - their sales funnel - as solutions to whatever problems you might have and enquired about.
This could amount anything from hundreds to thousands of dollars.
And that is ONLY for 1 site.
Even if they do offered discounts / downsells depending on how many sites you got, it still amounted to $1-2K per month.
How do I know this and why I said that, you might ask?
That's because I have spoken to both customer service support assistants from both Hostgator and SiteLock.