Possible hack? Images replaced on proxy server

I am responsible for several ASP and ASP.Net web sites that are hosted at an independent ISP. These sites were developed for a corporate client which has its own corporate network and firewall, completely separate from the ISP where these sites are hosted.

The other day, an employee of this corporation was surfing our site from within the corporate firewall and found one of our images was coming up as a porn image! Another employee was able to verify this.

Then we found that other images were coming up with no content, or as horizontal bars of color.

These problems are not occurring outside the corporate firewall; and the source images, on the server at the ISP, are fine. Only people behind this firewall see these bad images.

I suspect someone has hacked the corporate proxy server but I have no way to know for sure. I am in somewhat of a panic because naturally it does not reflect well on my little company to have porn images coming up on sites we develop.

I renamed the image in question and changed the IMG tag in the html, which fixed the problem for the time being. But I am worried about future.

Would a META HTTP-EQUIV="Pragma" CONTENT="no-cache" tag help?

What else can I do to prevent this, and, what can be causing this?

Do you need help?

In addition to our free technical library, Pantek provides professional IT services to companies who utilize Open Source software: Learn more about Pantek's Technical Support offerings Place an order for 24/7/365 Technical Support here Learn more about Pantek, who we are, and what we do Chat with a Live Operator Related securityfocus.com Links bugtraq certification focus-bsd focus-ids focus-ih focus-linux focus-ms focus-sun focus-unix-other focus-virus forensics incidents libnet linux-secnews ms-secnews pen-test secpapers secprog sectools secureshell security-basics securityjobs sf-news vuln-dev webappsec Request more information about Pantek

Thanks,
David Received on Sun Feb 9 11:36:52 2003