Jinja2 SSTI

👉 Overview

👀 What ?

Jinja2 Server-Side Template Injection (SSTI) is an attack technique used to exploit web applications that use the Jinja2 template engine in Python. It occurs when an attacker can control the data to be rendered by the Jinja2 template engine, allowing them to execute arbitrary code on the server.

🧐 Why ?

Understanding Jinja2 SSTI is crucial as it is a common vulnerability in web applications that use the Jinja2 template engine. Exploiting this vulnerability can lead to serious consequences such as data leakage, remote code execution, and even total system compromise. Therefore, it's important for developers and security professionals to understand Jinja2 SSTI to build secure applications and protect them from such attacks.

⛏️ How ?

To exploit Jinja2 SSTI, an attacker would first need to identify a point of injection where they can control the data being passed to the Jinja2 template engine. This could be in an HTTP request parameter, a cookie, or any other data source that the web application uses. Once an injection point is identified, the attacker can input specially crafted data that results in arbitrary code execution on the server.

⏳ When ?

Jinja2 SSTI attacks have been around as long as the Jinja2 template engine itself, which was first released in 2008. The popularity of the Jinja2 template engine and its widespread use in Python web applications have made Jinja2 SSTI a common attack vector.

⚙️ Technical Explanations

At the core of Jinja2 SSTI is the fact that the Jinja2 template engine allows the execution of Python code. This is by design, as it allows developers to build dynamic web pages. However, this also means that if an attacker can control the data being passed to the Jinja2 template engine, they can execute arbitrary Python code on the server. This is done by injecting code into the template, which is then executed by the template engine. The output of the executed code is then returned in the response, which can contain sensitive information or lead to further exploitation.