Knowing the specific category (Forensics, Web, or Pwn) will help pinpoint the exact solution.
: Even if files inside are encrypted or empty, the flag might be in plain text within the ZIP's binary or comments. Run strings InvisibleHack.zip | grep -i flag to check.
: A password-protected ZIP might be hidden inside another file (like an image) using tools like steghide . 2. Web: The "Invisible" Symlink Hack