If you're running the openX ad server and you're not running the latest version, I'd recommend doing an upgrade asap. There is a pretty bad exploit available and it's already hitting some big sites.
The exploit is done via the Open Flash Chart 2 module. There is no check in place to make sure users should be uploading the files in that directory. If you can't upgrade at this time then what you'll want to do is delete admin/plugins/videoReport/lib/ofc2/ofc_upload_image.php if you don't use the module. Most people don't use the module, and even if you do, I'd delete it anyway until you can upgrade.
There are a variety of ways to exploit this, but one thing you can check is look inside your admin/plugins/videoReport/lib/tmp-upload-images directory. If you see some sort of .php script in there, that's a bad sign.
