Ensure the header starts with 52 61 72 21 1A 07 (RAR 5.0) or 52 61 72 21 1A 07 00 (RAR 4.0).
The first step is to verify the file integrity and type to ensure it isn't a "polyglot" (a file that acts as two different formats at once). POST-09.rar
Attempting to list the contents often reveals if the archive is encrypted or contains multiple layers. Use unrar l POST-09.rar or 7z l POST-09.rar . Observations: Ensure the header starts with 52 61 72 21 1A 07 (RAR 5
If the archive is password-protected and no hint was provided in the challenge description: Use rar2john POST-09.rar > hash.txt . Use unrar l POST-09
Identify the archive's contents and retrieve the hidden flag or "secret" data. 1. Initial Identification
Check for appended data (files hidden after the end of the archive) using binwalk -e POST-09.rar . Hex Editing: Open the file in HxD or Ghex . Check for: