NSS [SWPUCTF 2022 新生赛]funny_php
开题，直接给了源码
<?phpsession_start();highlight_file(__FILE__);if(isset($_GET['num'])){if(strlen($_GET['num'])<=3&&$_GET['num']>999999999){echo ":D";$_SESSION['L1'] = 1;}else{echo ":C";}}if(isset($_GET['str'])){$str = preg_replace('/NSSCTF/',"",$_GET['str']);if($str === "NSSCTF"){echo "wow";$_SESSION['L2'] = 1;}else{echo $str;}}if(isset($_POST['md5_1'])&&isset($_POST['md5_2'])){if($_POST['md5_1']!==$_POST['md5_2']&&md5($_POST['md5_1'])==md5($_POST['md5_2'])){echo "Nice!";if(isset($_POST['md5_1'])&&isset($_POST['md5_2'])){if(is_string($_POST['md5_1'])&&is_string($_POST['md5_2'])){echo "yoxi!";$_SESSION['L3'] = 1;}else{echo "X(";}}}else{echo "G";echo $_POST['md5_1']."\n".$_POST['md5_2'];}}if(isset($_SESSION['L1'])&&isset($_SESSION['L2'])&&isset($_SESSION['L3'])){include('flag.php');echo $flag;}?>
php特性小零食。
三个关卡，第一关科学计数法，第二关双写绕过，第三关找两个md5后为0e开头的就行。
payload：
GET：?num=9e9&str=NSSNSSCTFCTF
POST：md5_1=s878926199a&md5_2=s155964671a
