500 Internal Server Error nginx

[polonus]

The page loads but on top I read 500 Internal Server Error and under it nginx  - recently the site came under cyberattack of some sort.
What is wrong here? http://www.telegraaf.nl/
Nothing given here: http://evuln.com/tools/malware-scanner/www.telegraaf.nl/
see: http://urlquery.net/queued.php?id=20162378
Header info
HTTP/1.1 403 no such site
Server: Varnish
Content-Type: text/html; charset=utf-8
Retry-After: 5
Content-Length: 398
Accept-Ranges: bytes
Date: Tue, 09 Apr 2013 16:26:36 GMT
X-Varnish: 1616501313
Age: 0
Via: 1.1 varnish
Connection: close
X-Served-By: rammstein
X-Cache: MISS

GET
HTTP/1.1 403 no such site
Server: Varnish
Content-Type: text/html; charset=utf-8
Retry-After: 5
Content-Length: 398
Accept-Ranges: bytes
Date: Tue, 09 Apr 2013 16:27:26 GMT
X-Varnish: 1616581474
Age: 0
Via: 1.1 varnish
Connection: close
X-Served-By: rammstein
X-Cache: MISS

See: http://urlquery.net/report.php?id=1897476
Second request delivered a normal result in the browser

polonus

[polonus]

Potentiallt suspicious files were flagged by Quttera's,
see image attached...