I didn't look at the file becuase it might have a payload. Regardless, they could have planted a script to control content on your pages, to facilitate cloaking, take over the entire server, compromise your email, any number of things.
The important thing is that your site is secured and the next issue to deal with is your rankings. This might be a matter of time, give it one month to two months so that over the course of an update that information can be flushed out and the original rankings return. In the meantime acquire high quality links for Yahoo to follow into your site so they know it's still there and attracting links.