I'm asked for credentials for s0.2mdn.net when browsing! Why? How do I stop it?

Question

Occasionally on my Media Center (running Windows 7) I have to download something from the internet to install. I use Internet Explorer 8 (over my normal favourite, Firefox) simply because it's there.

However whenever I browse sites, I keep getting a pop-up entitled "Windows Security" with the following message:

The server s0.2mdn.net at requires a username and password

Warning: This server is requesting that your username and password be sent in an insecure manner (basic authentication without a secure connection)

(there is a double space between "at" and "requires a username")

I'm fully aware of how sites can be set up for basic security but I've never heard of this site, I don't seem to find out much about it apart from that it seems to belong to doubleclick (online ads) and I have no idea why it is popping up authentication requests. I never see it when I browse on IE or Firefox on any of the other computers.

Any ideas what is it and how I stop it doing this? At present, I just hit Cancel until it goes away.

Answer 1

It sounds like that computer might have different proxy or dns settings from the others.

If you haven't changed these values then that might indicate that there is some malware present.

Double check the "LAN Settings" in IE (Tools > Internet Options > Connections) and the DNS settings on your network connection (TCP/IP Properties > General tab). If these are different to the other two reset them and see if the problem goes away.

By changing either of these the malware will be forcing you to either connect to the internet via their proxy, or redirecting you when you try to access certain sites. This would either stop you accessing anti-virus sites or put up fake versions of other sites.

Also run an anti-virus scan.

Answer 2

DoubleClick has been acquired by Google, and perhaps the Google credentials are not being transferred correctly.