# You are not allowed

#### Category : Reverse engineering
#### Points : 100 (242 solves)

## Challenge
Can you reverse this program and get us the flag?

Flag format: flag{string}

Attachment : program

## Solution
Using file command on this binary, we see that it is a stripped binary.

Opening this binary in ghidra and going to the `entry` function, the first parameter of `__libc_start_main` is the main function.


Double clicking it, we get the main function.


So it is taking input from the user and then comparing it with a secret key generated by `FUN_00401242`.

Taking a look at this function,


So we just need to convert the integer into char and we will get the secret key which we can then enter to get the flag.

The key obtained from this is `Sup3rS3cr3tK3y#`

Entering this, we get the flag


So the flag is `flag{1ntr0_t0_r3v3rs3_3ng1n33r1ng}`

Original writeup (https://github.com/p1xxxel/ctf-writeups/tree/main/2021/RCTS%20CERT%202021/You%20are%20not%20allowed).