Well - it's no dDOS attack - how to attack MySQL socket ? If it's really dDOS - which I highly doubt - it's an attack on the webserver though it seems that was running.
Second - don't waste your time with a firewall - this won't help at all against script based attacks and for sure not against Denial of Service attacks - except you block everything

About the problem - reupload all files taken from the original sources and only from there. Then try to run some MySQL optimization scripts to see if there's a bottleneck somewhere.
Also - check if HTML is enabled anywhere (Posts, Signatures etc.) - if so - it maybe wasn't a real attack, someone could post:
Quote:
<html>
<head>
<script type="text/javascript">
alert("You got hacked");
</script>
</head>
<body></body></html>
|
Which is neither a security problem nor a hack.