Python - CSS Injection (CSSI)

Running the app on Docker

$ sudo docker pull blabla1337/owasp-skf-lab:cssi

$ sudo docker run -ti -p 127.0.0.1:5000:5000 blabla1337/owasp-skf-lab:cssi

Now that the app is running let's go hacking!

Reconnaissance

When we start the application we can see that there is a text box that allow you to write a color name.

We can write a color like:

And depending on the color that we chose, this will be the color in the text below:

Exploitation

If we check how the text that we wrote in the text box is later put into the code we can see:

If we try to insert a malicious code that we know it will be inserted in the source code, we can try something like this:

This code should show an alert box or pop up alerting the text "CSSI - XSS". If we check the website after sending the malicious request:

And goal achieved!

Additional sources

https://www.owasp.org/index.php/Testing_for_CSS_Injection_(OTG-CLIENT-005)