# Grace Hopper

## Description  
> Grace Brewster Hopper (née Murray; December 9, 1906 – January 1, 1992) was
> an American computer scientist, mathematician, and United States Navy rear
> admiral. One of the first programmers of the Harvard Mark I computer, she
> was a pioneer of computer programming who invented one of the first linkers.
> Hopper was the first to devise the theory of machine-independent programming
> languages, and the FLOW-MATIC programming language she created using this
> theory was later extended to create COBOL, an early high-level programming
> language still in use today. - Wikipedia Entry

> Chal: Command this webapp like this Navy Real Admiral

## Challenge URL  
[Challenge Link](https://cyberheroines-web-srv2.chals.io/vulnerable.php)

## Solution  
* The challenge says to enter a command but `ls` does not work.   
```  
Output:  
You think it's that easy? Try harder!  
```  
* Use `dir -a` to list directory contents even hidden files  
![dir](https://i.imgur.com/lCgZ68j.png)  
* `ls`, `cat`, `more`, `less`, `head`, `tail` commands are blacklisted.  
* So to view file contents, we can use `strings` or just `grep` for the flag format to view file contents  
* Running `strings` on `cyberheroines.sh` gives us the flag  
```  
FLAG="CHCTF{t#!$_!s_T#3_w@Y}"  
echo -n "$FLAG" | sha256sum > cyberheroines.txt  
```

### FLAG  
```  
CHCTF{t#!$_!s_T#3_w@Y}  
```

Original writeup (https://github.com/HarshJolad/CTF-
Writeups/tree/master/CyberHeroines-CTF-2023/web/Grace_Hopper#grace-hopper).