网站
http://www.57see.com/前几天遭黑客入侵，后台显示异常，显示Web攻击。后来网站上右下角偶尔跳出广告，瑞星联盟没有提示有木马，网页上没有发现挂马代码，广告有时一个小时会出现，没有规律，跳出广告的代码如下：
<div id="LELE_ShowDIV_UNIONtop" style="position: fixed; z-index: 2147483647; bottom: 0px; right: 0px; overflow: visible;"><div id="LELE_ShowDIV_UNION" style="position: fixed; z-index: 2147483647; bottom: 0px; right: 0px; overflow: hidden;"><div id="_33" style="z-index: 2147483648; cursor: pointer; top: 6px; left: 242px; width: 25px; height: 13px; display: block; position: absolute;"><img style="width:56px; height:23px;padding:0px;border:0px;" src="http://ad.daohang365.net:8089/99vjj/images/close.jpg"></div><div id="adfdiv" style="margin: 0px; padding: 0px; width: 300px; height: 250px;"><div style="position:absolute;z-index:1"></div> <iframe id="adIframe" name="adIframe" src="http://www.gamegogo.net/?link=aHR0cDovL3d3dy5nYW1lZ29nby5uZXQvYWQvaHktZ20uaHRtbA==" height="250" width="300" scrolling="no" frameborder="0"> </iframe> </div></div><div id="LELE_ShowDIV_UNION_REPLAY" style="position: fixed; z-index: 2147483647; bottom: 0px; right: 0px; overflow: hidden; display: none;"><div style="z-index: 2147483646; cursor: pointer; bottom: 0px; right: 0px; width: 60px; height: 65px;"><img style="width:60px; height:65px;padding:0px;border:0px;" src="http://img.sp.cc/d/chongbo.png"></div></div></div>
现在我应该如何处理呢？
用户系统信息：Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.152 Safari/537.36