In this challenge you will get a a netcat and a linux binary file and once run

```
welcome to the guessing game!
guess what I'm thinking
```

The main focus of this challenge is the binary file and using ghidra we could dump the binary and get a rough c code but for this challenge its we got the logic right away.

```
undefined8 main(void)

{
int iVar1;
undefined8 uVar2;
long in_FS_OFFSET;
int local_a4;
FILE *local_a0;
char local_98 [64];
char local_58 [72];
long local_10;

local_10 = *(long *)(in_FS_OFFSET + 0x28);
setbuf(stdout,(char *)0x0);
puts("welcome to the guessing game!");
puts("guess what I\'m thinking");
fgets(local_98,0x40,stdin);
iVar1 = strcmp(local_98,"nuh uh pls nolfjdl\n");
if (iVar1 == 0) {
puts("please guess a number between 0 and 100:");
__isoc99_scanf(&DAT_00102089,&local_a4);
if ((int)(0x17a / (long)local_a4) + 3 == local_a4) {
puts("congratulations! you guessed the correct number!");
}
else {
puts("sorry, you guessed the wrong number!");
}
local_a0 = fopen("flag.txt","r");
if (local_a0 == (FILE *)0x0) {
puts("flag.txt not found - ping us on discord if you are running this on the server");
uVar2 = 1;
}
else {
fgets(local_58,0x40,local_a0);
puts(local_58);
uVar2 = 0;
}
}
else {
puts("nuh uh!");
uVar2 = 1;
}
if (local_10 != *(long *)(in_FS_OFFSET + 0x28)) {
/* WARNING: Subroutine does not return */
__stack_chk_fail();
}
return uVar2;
}
```

here on

```
puts("welcome to the guessing game!");
puts("guess what I\'m thinking");
fgets(local_98,0x40,stdin);
iVar1 = strcmp(local_98,"nuh uh pls nolfjdl\n");
```

we got a fgets and it will get a value local_98 and a string **"nuh uh pls nolfjdl"** and entering **"nuh uh pls nolfjdl"** we get the:

> please guess a number between 0 and 100:

```
if ((int)(0x17a / (long)local_a4) + 3 == local_a4) {
puts("congratulations! you guessed the correct number!");
}
else {
puts("sorry, you guessed the wrong number!");
}
```

this is dosen't need to be overcomplicated because what ever you'll do it will go to the end to the:

```
local_a0 = fopen("flag.txt","r");
```

--------------------------------------------------------------------------
Full output:

```
$ nc tjc.tf 31478
welcome to the guessing game!
guess what I'm thinking
nuh uh pls nolfjdl
please guess a number between 0 and 100:
90
sorry, you guessed the wrong number!
tjctf{n3v3r_c0uld_r34d_y0ur_m1nd_8e6646a1}
```

> tjctf{n3v3r_c0uld_r34d_y0ur_m1nd_8e6646a1}