sitemap_7.php file found via Google Fetch, can't find/access in browser/FTP/SSH

I'm pulling my hair out right now and I can't seem to narrow down this hack.

Google Fetch & Render inside Webmaster Tools is finding a /sitemap_7.php file on our server that just isn't there -- in either the files via the browser/ftp/ssh.

http://ift.tt/1SSFKP2

I've scanned the site in every way I can. I just can't find the file.

Can anyone help?

via Chebli Mohamed