Depending on what was found in the archive, use these specialized techniques:
Checking the archive's structure often reveals clues about the challenge type (e.g., steganography or forensics).
: Generate MD5 or SHA-256 hashes ( sha256sum Space.Invaders.Extreme.zip ) to ensure the file hasn't been tampered with and to check against known databases like VirusTotal . 2. Archive Inspection File: Space.Invaders.Extreme.zip ...
: Use these tools to see if other files are embedded inside the extracted files. For example, a PNG file might actually have a ZIP appended to the end of it.
The "flag" is usually the final prize, often formatted as FLAG{...} or CTF{...} . In some forensics challenges, the flag may be hidden in the ZIP's or within alternative data streams (ADS) if the file was handled on a Windows system. Depending on what was found in the archive,
: If an executable is present, load it into Ghidra or IDA Pro . Analyze the logic—specifically where it handles input or "victory" conditions—to find where the flag is generated or stored in memory. 4. Extracting the Flag
: Run strings on the zip and any extracted binaries. Look for readable text, URLs, or base64-encoded strings that might be the flag. Archive Inspection : Use these tools to see
: If the archive is password-protected, tools like John the Ripper or hashcat are used to crack the ZIP password using wordlists like rockyou.txt . 3. Deep Analysis Techniques