Spam link inside my posts, need help!

Hi all,

I recently found that many of my posts have hidden spam links embedded into my post. Below is one example from my post HERE:

<div style="position:absolute;top:-9814px;left:-5628px;"><a href="https://www.upstartblogger.com/true-grit-movie">true grit dvds</a></div>

Looks like these links are positioned outside the viewing area so that I didn’t notice them before with a web browser.

I have a few hundred posts on my wordpress blog. I searched the database for key word ‘position:absolute’ and found nearly 800 of them. Deleting all the spam links may take considerable amount of time. Could anyone suggest a good way of removing them and preventing the spam links from showing up again?

Thanks!

PS. My wordpress version is 3.1.3