Definition
Template injection is a security vulnerability that occurs when attackers inject malicious code into a web application template. Many modern web frameworks use templates to isolate the presentation logic from the application’s business logic.
A hacker can compromise a user-supplied input to insert malicious code into a template, which the server-side rendering engine executes.
Developers use templates to generate dynamic content and define reusable layouts. Failure to properly validate user input before inserting it into the template enables hackers to compromise it through template injection.
How Template Injection Works
- Identifying vulnerable applications: Hackers target web applications that display dynamic content with templates. Some common targets include blogging platforms, content management systems (CMS), and e-commerce platforms.
- Exploiting input fields: The attacker locates an input point in the web application where they can inject the malicious code. They can design this code to perform arbitrary commands, access sensitive information, or remotely control the server.
- Malicious input execution: After the malicious input is injected into the template, the rendering process processes and executes it, resulting in various security risks.
Dangers of Template Injection
- Remote code execution: Attackers can use template injection to inject arbitrary code on the server, gaining control of the application and potentially the underlying server.
- Denial of service: Attackers can inject commands that cause the server to freeze, crash, or consume excessive resources, resulting in denial of service (DOS).
- Data leakage: An attacker can inject template-specific codes to access sensitive information within the application or its environment.