For this challenge, we were given a pcapng file. The flag is meant to be CYBERTF{c2 framework used in leet speak}. Running strings on the capture, we see:

$ strings c2.pcapng
...
3d77
7o0~
b|}p
l69s
Covenant0
210520070857Z
310519070857Z0
Covenant0
~vVz"/
loq5
...

Covenant is a well known C2 framework. The flag is CYBERTF{C0V3N4NT}.

You can view the sources on github or read other writeups.