Recovering from hack

RESOLVED

After all the effort I started running diagnostics on my host. Somewhere along the way my domain had been downgraded to PHP Version 5.2.17. I got it back to 5.3.2 and now everything magically works just fine.

Part of the reason for the hack may be that you are running on 5.3.2. The current version of PHP is 7.1.0.

Old versions of software are always unsecure. (A list of 5.3.2 security vulnerabilities is here: https://www.cvedetails.com/vulnerability-list/vendor_id-74/product_id-128/version_id-90936/PHP-PHP-5.3.2.html)

PHP 5.3 reached its end of life in August 2014. For security purposes, you should upgrade to at least 5.6, which will still have security support until the end of 2018.