Like most of the the shared hosting servers, hackers usually will look for a way to pick out vulnerable WordPress or other open source powered website and inject malicious code and run it.
We are facing this kind of hacking most of the time. We are not able to stop all these hacking because mostly 80% of our web hosting clients are using WordPress. Some of them will take care of their site, some of them don’t. And those that don’t update their site’s system regularly constantly targeted by hackers to inject malicious files in it.
Our solution is to have an anti virus in our shared hosting to make sure the rest of the account doesn’t infected and there isn’t any suspicious activities happening in the system.
Every single day we will run a virus scan on all the files in our hosting account and quarantine them if there are any suspicious files.