> For the complete documentation index, see [llms.txt](https://gitbook-88.gitbook.io/ctf-writeup/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gitbook-88.gitbook.io/ctf-writeup/ba-chang/gong-fang-shi-jie/backup.md).

# backup

备份文件后缀.bak，在网址后添加index.php.bak即可得到文件，打开获得flag。