I didn’t check all the challenges this time because when I joined the competition, most of the challenges already solved by my teammates lol

I love JavaScript(yep, including those weird features) and XS-leak, so this writeup will talk about only two challenges:

  1. web/Sustenance
  2. misc/CaaSio PSE

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Among the many web vulnerabilities, my favorite is prototype pollution. It can be powerful sometimes when you find a script gadget.

So, I decided to make an XSS challenge about prototype pollution.

In April, the challenge I made was released on Intigriti, if you haven’t checked that one, here is the link:

Making a good challenge is hard.

I made a few mistakes. With the bugs I made, the challenge became much easier. To make up for it, I decided to make another one, called “The Revenge of Intigriti 0422 Challenge”.

Below is the intended solution to the revenge challenge.

Challenge URL:

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There were two difficult Web questions this time. I solved one, and the other one was unsolvable, but the solution is worth a look. Here’s a brief summary.

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If you want to generate a new window on a webpage, there are probably only two options: one is to embed resources on the same page using tags such as iframe, embed, and object, and the other is to use to open a new window.

As a front-end developer, I believe that everyone is familiar with these. You may have used iframe to embed third-party web pages or widgets, or used to open a new window and communicate with the original window through window.opener.

However, from a security perspective, there are many interesting things about iframes, which often appear in the real world or in CTF competitions. Therefore, I want to record some of the features I learned recently through this article.

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