Thanks Suman Maharjan for the answer, but still I would like to know what is this:
/_auto.js?_req=LzIwMTcvMTAvMDUvZGVzY29iZXJ0by11bi1jb3VwbGUtZnJhbmNvLXBvcnR1Z2Fpcy1wcm9kdWl0LWR1LXNhZnJhbi1hdS1wb3J0dWdhbC8%3D
I have Login With Ajax plugin, is it about that?
I can delete all intrusions like this, just for not appearing in admin board?
Thanks again!