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# TU CTF 2018 - hardDOS

## Description
Paying attention is mitey important! (Difficulty: Hard)

nc 18.216.100.42 12345

## Solution
This challenge is similar to [easyDOS](../easyDOS), we have to find the correct commands and arguments.

Also in this case we have to answer some questions before reaching the real challenge.

![msg1](./img/msg1.png)

Let's just pick one of them.

![msg2](./img/msg2.png)

Of course yes!

Now the real challenge starts. Apparently `THE MITE` is giving us some hints.

`"THE MITE: First thing's first. What's even in here?"`

This step was fairly easy, `ls` is working! We got a list of files and a new hint.

`"THE MITE: Alright, seems like a standard DOS installation. One of these files must to have something in it."`

We lost quite a lot of time before discovering that the correct command was `file`. Knowing that we iterate over all files.

`"THE MITE: Hey now, GRAPHICS.COM should be a DOS executable!"`

So `GRAPHICS.COM` is the file we are interested in. Eventually one of us tried to do `strings GRAPHICS.COM`, which gave us the content of the file and the flag!

```
TUCTF{4LW4Y5_1NF3C7_7H353_19742_BY735}
```

## Code
[flag.py](./flag.py)

## Cascade
Note that the server was infected by [Cascade](http://malware.wikia.com/wiki/Cascade). Once connected, we only had three minutes before it hits.

Original writeup (https://github.com/ctf-epfl/writeups/tree/master/tuctf18/hardDOS#tu-ctf-2018---harddos).