[pwnable.kr] fd (1pt) write up

 Mommy! what is a file descriptor in Linux?

* try to play the wargame your self but if you are ABSOLUTE beginner, follow this tutorial link:

https://youtu.be/971eZhMHQQw

ssh [email protected] -p2222 (pw:guest)

 fd@pwnable:~$ cat fd.c

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

char buf[32];

int main(int argc, char* argv[], char* envp[]){

if(argc<2){

printf("pass argv[1] a number\n");

return 0;

}

int fd = atoi( argv[1] ) - 0x1234;

int len = 0;

len = read(fd, buf, 32);

if(!strcmp("LETMEWIN\n", buf)){

printf("good job :)\n");

system("/bin/cat flag");

exit(0);

}

printf("learn about Linux file IO\n");

return 0;

}