Snap Creek Duplicator WordPress plugin code injection

When the WordPress plugin Snap Creek Duplicator restores a backup, it
leaves dangerous files in the filesystem such as installer.php and
installer-backup.php. These files allow anyone to call a function that
overwrite the wp-config.php file AND this function does not sanitize
POST parameters before inserting them inside the wp-config.php file,
leading to arbitrary PHP code execution.
WARNING: This exploit WILL break the wp-config.php file. If possible try
to restore backups of the configuration after the exploit to make the
WordPress site work again.