dont-use-client-side PicoCTF 2019 (web)

Description

Can you break into this super secure portal? https://jupiter.challenges.picoctf.org/problem/37821/ (link) or http://jupiter.challenges.picoctf.org:37821

Hints

Never trust the client

Solution

View source on the challenge page. Notice the verify function. Construct the string that would pass that check.

Final flag: picoCTF{no_clients_plz_1a3c89}