WARNING, malware will make pop-up on your site

Please do not post links to suspicious places in these forums, OK?

*Looks*

I’ve downloaded and looked at the source code.

https://plugins.trac.www.ads-software.com/browser/menu-image/trunk

I don’t see anything that could do what you’ve said. Where in the source code does the plugin do that?

It may be that your site was hacked and if so please follow this guide.

When you’re done, you may want to implement some (if not all) of the recommended security measures.