Exploiting SSI Injection

Exploiting Server-Side Includes (SSI) injection involves leveraging vulnerabilities in web applications that improperly handle user input.

Consider a sample web application that presents a simple form asking for a name. When a user submits their name, they are redirected to a page with a .shtml extension, which suggests that SSI may be supported.

To test for SSI injection, you can input a username like <!--#printenv -->. If the application is vulnerable and does not sanitize the input, this directive will be executed, and the environment variables will be displayed on the page. This confirms the presence of an SSI injection vulnerability.

Exploitation Process

• Identifying Vulnerabilities:

  • Access the Web Application:

    • Navigate to the application URL: http://<SERVER_IP>:<PORT>/

  • Input Form:

    • You will see a simple form asking for your name.

• Testing for SSI Injection:

  • Enter a Test Input:

    • Input the following SSI command as your username: <!--#printenv -->

  • Observe the Output:

    • If the application executes this command, it will display environment variables, indicating an SSI injection vulnerability.

• Exploiting the Vulnerability:

  • Execute Arbitrary Commands:

    • To further test the vulnerability, input: <!--#exec cmd="id" -->

    • This command will execute on the server, revealing user and group IDs, demonstrating the potential for arbitrary command execution.