[TFC CTF 2022] random

1. 개요

 16진수 문제

 

2. 분석

입력값이 0x539와 같아야합니다.

 

0x539는 16진수이고 10진수 1337과 같습니다.

 

1337을 입력해줍니다.

undefined8 main(void)

{
  uint uVar1;
  time_t tVar2;
  char *pcVar3;
  long in_FS_OFFSET;
  int local_14;
  long local_10;
  
  local_10 = *(long *)(in_FS_OFFSET + 0x28);
  setvbuf(stdin,(char *)0x0,2,0);
  setvbuf(stdout,(char *)0x0,2,0);
  setvbuf(stderr,(char *)0x0,2,0);
  tVar2 = time((time_t *)0x0);
  srand((uint)tVar2);
  puts("Menu: \n1. Generate number");
  __isoc99_scanf(&DAT_0010201e,&local_14);
  if (local_14 == 1) {
    uVar1 = rand();
    printf("%d",(ulong)uVar1);
  }
  else {
    if (local_14 == 0x539) {
      pcVar3 = getenv("FLAG");
      printf("%s",pcVar3);
    }
    else {
      printf("wrong option");
    }
  }
  if (local_10 != *(long *)(in_FS_OFFSET + 0x28)) {
                    /* WARNING: Subroutine does not return */
    __stack_chk_fail();
  }
  return 0;
}