<?php
    // from https://github.com/orangetw/My-CTF-Web-Challenges#babyfirst

    highlight_file(__FILE__);
    
    $dir = 'sandbox/' . md5("parcham" . $_SERVER['HTTP_X_FORWARDED_FOR']);
    if ( !file_exists($dir) )
        mkdir($dir);
    chdir($dir);
    
    $args = $_GET['args'];
    for ( $i=0; $i<count($args); $i++ ){
        if ( !preg_match('/^\w+$/', $args[$i]) )
            exit();
    }
    exec("/bin/orange " . implode(" ", $args));
?>

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Warning: chdir(): No such file or directory (errno 2) in /code/index.php on line 9

Warning: implode(): Invalid arguments passed in /code/index.php on line 16