[网鼎杯 2020 朱雀组]phpweb

 看它一直在相同的时间刷新，那就抓包看看

 一个date，还有参数，应该是在func上选择函数，p选择函数参数，试一试file_get_contents函数，p上输入index.php。

<?php
    $disable_fun = array("exec","shell_exec","system","passthru","proc_open","show_source","phpinfo","popen","dl","eval","proc_terminate","touch","escapeshellcmd","escapeshellarg"
,"assert","substr_replace","call_user_func_array","call_user_func","array_filter", "array_walk",  "array_map","registregister_shutdown_function","register_tick_function","filter_var", 
"filter_var_array", "uasort", "uksort", "array_reduce","array_walk", "array_walk_recursive","pcntl_exec","fopen","fwrite","file_put_contents");
    function gettime($func, $p) {
        $result = call_user_func($func, $p);
        $a= gettype($result);
        if ($a == "string") {
            return $result;
        } else {return "";}
    }
    class Test {
        var $p = "Y-m-d h:i:s a";
        var $func = "date";
        function __destruct() {
            if ($this->func != "") {
                echo gettime($this->func, $this->p);
            }
        }
    }
    $func = $_REQUEST["func"];
    $p = $_REQUEST["p"];

    if ($func != null) {
        $func = strtolower($func);
        if (!in_array($func,$disable_fun)) {
            echo gettime($func, $p);
        }else {
            die("Hacker...");
        }
    }
    ?>

call_user_func函数是一种调用函数的方式

gettype() 函数用于获取变量的类型。

func中不能含有disable_fun变量里的字符

今天学到一个，有类，没有过滤unserialize函数，所以可以用这个

 

 看根目录没有flag文件，这里不知道了，一个一个看太累，就看wp，说用find / -name flag*

find +目录 +条件 +条件值

 可以用读取文件的函数来读取flag，比如file_get_contents，readfile，highlight_file等函数