Wordfence Security is my preferred solution. It has an easy and automated scanner that check for malicious code and can compare the WordPress, Theme and Plugins files with the original WordPress library, allow you to view the differences and revert to original version of file or delete it. Wordfence has a firewall preventing malicious scripts from operating, a built in traffic log which allows you to block bad IP addresses, a method to automatically limit fake crawlers and limit and block login attempts by hackers.
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