404 Error And Admin Brute Force Attack

I see a lot of brute force attack against admin and admin users to my site. Thanks for your plugin protection and it saved my life.

I suspect that the hacker wrote some malware in my site. I see lot of 404 error when accessing almost all posts and it is pointing out this file below is missing:
/wp-content/themes/mytheme/Genericons.eot and
/wp-content/themes/mytheme/Genericons.svg

I confirmed with theme-dev team and they confirmed there is no such file supposed to be there in that location.
Also when I am clicking the details link on 404 error, the pop-up window is blank and no details are displaying.

I am just wondering is this a false alarm or iTheme security pointing out to some malware file saved in my theme folder. I really appreciate your advice.

https://wordpress.org/plugins/better-wp-security/