Nebula is part of Exploit Exercises, it covers a variety of simple and intermediate challenges that cover Linux privilege escalation, common scripting language issues, and file system race conditions.
This level requires you to find a Set User ID program that will run as the “flag00” account. You could also find this by carefully looking in top level directories in / for suspicious looking directories. Alternatively, look at the find man page.
In this first level, you have to find a file owned by
flag00 with suid bit.
A single command can do the trick:
find / -user flag00 -perm /6000