This is the code Comcast is injecting into its users web traffic.

<script language="JavaScript"type="text/javascript">

// Comcast Cable Communications, LLC Proprietary. Copyright 2012.

// Intended use is to display browser notifications for critical and time sensitive alerts.

varSYS_URL='/e8f6b078-0f35-11de-85c5-efc5ef23aa1f/aupm/notify.do';

// var image_url='http://servicealerts.comcast.net:8080/images/mt';

varimage_url='http://xfinity.comcast.net/constantguard/BotAssistance/notice/images';

varheadertext1='<strong>Comcast Courtesy Notice</strong>';

vartextline1='You have reached 90% of your <b>monthly data usage allowance</b>.';

vartextline2='Please sign in for more information and to remove this alert.';

varacknowledgebutton='<a href=\"#\" onClick="document.location.href=\''+SYS_URL+'?dispatch=redirect&redirectName=login&paramName=bmUid\'" title="Sign in to acknowledge" style="color: #FFFFFF;"><img alt="Sign in to acknowledge" src="'+image_url+'/mt_signin.png"/></a>';

varverifybulletin='<a href="http://customer.comcast.com/help-and-support/internet/data-usage-plans-nash/" target="_new">How do I know this message is from Comcast?</a>';

if(self.location==top.location){

document.write('<style type="text/css">');

document.write('#comcast_content {width: 600px; height:240px; box-shadow: 10px 10px 5px #888; background: #fff; border: 1px solid #454545; position:absolute; top:50px; left:100px; zoom:1; z-index: 9999999; opacity:0.90; filter:alpha(opacity=90);}');

document.write('#comcast_content .header {height: 35px; background:url('+image_url+'/headerbg.gif) repeat-x;}');

document.write('#comcast_content .a {color: #00a3e0;}');

document.write('#comcast_content .logo {float:left;}');

document.write('#comcast_content .content-wrapper {padding-left: 18px; padding-right: 15px; padding-bottom: 12px;}');

document.write('#comcast_content .headerimage { margin-top: 15px;}');

document.write('#comcast_content .header1 {margin: 18px 0 0 0; color: #C00000; padding: 3px; font: 23px/24px bold Arial, Helvetica, sans-serif;}');

document.write('#comcast_content .textcontent {margin: 12px 0 0 0; text-align: center; color: #303030; word-spacing: 0px; font: 14px/15px Arial, Helvetica, sans-serif; line-height: 1.20;}');

document.write('#comcast_content .acknowledge {padding-top:6px; text-align: center;}');

document.write('#comcast_content .how-do-i {float:left; position:absolute; bottom:20px; left:18px; margin: 12px 0 0 0; font: 13px/14px bold Arial, Helvetica, sans-serif; text-align: bottom;}');

document.write('#comcast_content .comcast-wrapper {float:right; position:absolute; bottom:15px; right:18px; padding-top:0px; text-align: right;}');

document.write('</style>');

document.write('<div class="main-wrapper" id="comcast_content">');

document.write('<div class="header" onmousedown="javascript:dragStart(event,\'comcast_content\')">');

document.write('<img src="'+image_url+'/xfinity-logo.gif" alt="Xfinity" class="logo"/>');

document.write('</div>');

document.write('<div class="content-wrapper">');

document.write('<p class="header1">');

document.write(headertext1);

document.write('</p>');

document.write('<p class="textcontent">');

document.write(textline1);

document.write('</p>');

document.write('<p class="textcontent">');

document.write(textline2);

document.write('</p>');

document.write('<p class="how-do-i">');

document.write(verifybulletin);

document.write('</p>');

document.write('<div class="acknowledge">');

document.write(acknowledgebutton);

document.write('</div>');

document.write('<div class="comcast-wrapper">');

document.write('<img src="'+image_url+'/message-by-comcast.gif" alt="Message by Comcast"/>');

document.write('</div>');

document.write('</div>');

document.write('</div>');

}

// Function to Determine browser and version. Copyright 2001 by Mike Hall.

// See http://www.brainjar.com for terms of use.

functionBrowser(){

varua,s,i;

this.isIE=false;

this.isNS=false;

this.version=null;

ua=navigator.userAgent;

s="MSIE";

if((i=ua.indexOf(s))>=1){

this.isIE=true;this.version=parseFloat(ua.substr(i+s.length));return;

}

s="Netscape6/";

if((i=ua.indexOf(s))>=0){

this.isNS=true;this.version=parseFloat(ua.substr(i+s.length));return;

}

s="Gecko";

if((i=ua.indexOf(s))>=0){

this.isNS=true;this.version=6.1;return;

}

}

varbrowser1=newBrowser();

vardragObj=newObject();

dragObj.zIndex=99999;

functiondragStart(event,id){

varel;

varx,y;

if(id)dragObj.elNode=document.getElementById(id);

else{

if(browser1.isIE)dragObj.elNode=window.event.srcElement;

if(browser1.isNS)dragObj.elNode=event.target;

if(dragObj.elNode.nodeType==3)dragObj.elNode=dragObj.elNode.parentNode;

}

if(browser1.isIE){

x=window.event.clientX+document.documentElement.scrollLeft+document.body.scrollLeft;

y=window.event.clientY+document.documentElement.scrollTop+document.body.scrollTop;

}

if(browser1.isNS){

x=event.clientX+window.scrollX;

y=event.clientY+window.scrollY;

}

dragObj.cursorStartX=x;

dragObj.cursorStartY=y;

dragObj.elStartLeft=parseInt(dragObj.elNode.style.left,10);

dragObj.elStartTop=parseInt(dragObj.elNode.style.top,10);

if(isNaN(dragObj.elStartLeft))dragObj.elStartLeft=100;

if(isNaN(dragObj.elStartTop))dragObj.elStartTop=50;

if(browser1.isIE){

document.attachEvent("onmousemove",dragGo);

document.attachEvent("onmouseup",dragStop);

window.event.cancelBubble=true;

window.event.returnValue=false;}

if(browser1.isNS){

document.addEventListener("mousemove",dragGo,true);

document.addEventListener("mouseup",dragStop,true);

event.preventDefault();

}

}

// End Function

functiondragGo(event){

varx,y;

if(browser1.isIE){

x=window.event.clientX+document.documentElement.scrollLeft+document.body.scrollLeft;

y=window.event.clientY+document.documentElement.scrollTop+document.body.scrollTop;

}

if(browser1.isNS){

x=event.clientX+window.scrollX;y=event.clientY+window.scrollY;

}

dragObj.elNode.style.left=(dragObj.elStartLeft+x-dragObj.cursorStartX)+"px";

dragObj.elNode.style.top=(dragObj.elStartTop+y-dragObj.cursorStartY)+"px";

if(browser1.isIE){window.event.cancelBubble=true;window.event.returnValue=false;}

if(browser1.isNS)event.preventDefault();}

functiondragStop(event){

if(browser1.isIE){

document.detachEvent("onmousemove",dragGo);

document.detachEvent("onmouseup",dragStop);

}

if(browser1.isNS){

document.removeEventListener("mousemove",dragGo,true);

document.removeEventListener("mouseup",dragStop,true);

}

}

varxmlhttp=false;/*@cc_on @*//*@if (@_jscript_version >= 5) try { xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (E) { xmlhttp = false; } } @end @*/if(!xmlhttp&&typeofXMLHttpRequest!='undefined'){try{xmlhttp=newXMLHttpRequest();}catch(e){xmlhttp=false;}}if(!xmlhttp&&window.createRequest){try{xmlhttp=window.createRequest();}catch(e){xmlhttp=false;}}

functionacknowledge(){sendAck();document.getElementById('comcast_content').style.display="none";}

functionsendAck(){xmlhttp.open("GET",SYS_URL+'?dispatch=ackBulletin',true);xmlhttp.send(null)}

varcomcastCheck=1;

varcomcastTimer;

functioncheckBulletin(){

if(comcastCheck==0){return;}

xmlhttp.open("GET",SYS_URL+'?dispatch=checkBulletin',true);

xmlhttp.onreadystatechange=function(){

if(xmlhttp.readyState==4){

if(xmlhttp.responseText.indexOf('43a1028c-7d11-11de-b687-1f15c5ad6a13')==-1){

document.getElementById('comcast_content').style.display="none";

comcastCheck=1;

}

comcastTimer=setTimeout("checkBulletin()",5000);

};

};

xmlhttp.send(null);

}

checkBulletin();

</script>