Question

I got the following warning & error by the chrome browser while trying to access my webpage via https.

Warning: The page at about:blank displayed insecure content from http://subdomain.name.dns-stuff.com/go.php?sid=mix.

Error: Failed to load resource: the server responded with a status of 404 (Not Found)

Should i start worrying?
How can i find where this insecure content comes from?

UPDATE: A malicious IFRAME can source in content from web pages that attempt to fingerprint and exploit a browser vulnerability or client/OS vulnerability to cause a drive-by-download. Such IFRAMEs are typically invisible to users.

http://wam.dasient.com/wam/infection_library/917395c589f265fd940fc7cc9b0df341/dns-stuff

Answer 1

After contacting the hosting provider of mine they managed to find that the webpage was infected. Actually a part of the jquery.js was infected.

Lessons learned.

1. Never download the jquery libraries (or anything) from any place of the web, except the official ones.
2. Keep up to the latest versions via links to the official sites.