Infected website ! Help guys !

Hi guys,

When i access my admin section after logging in, i get each time a warning from avast telling me that a file called quicktags.min.js?ver=3.8.4|{gzip} is infected by a JS:Iframe-EJR [Trj].

besides, i’m receiving an important number of people trying to access my admin section. The iThemes Security Plugin reports more than 20 to 30 tries per day.

I’m using for the login form now 2 plugins : Two factor auth and Si CAPTCHA Option.

Is there any way to replace that file?

PS : sorry for my english.