In a CTF environment, the "write-up" would conclude with the discovery of a "flag" (a specific string like CTF{Stepmom_Caught_Red_Handed} ) hidden deep within the file's code or memory strings.
The actual "evil" part is often encoded (Base64 or Hex) to hide its true intent from basic antivirus software.
Before opening the file, analysts look at it from the outside: