XLS to XLSX: The Hilarious Hash Collision Conundrum

Discover the quirky world of spreadsheet formats: Open a protected .xls file, save it as .xlsx, and watch as the OOXML file adopts the 16-bit hash from the original OLE file.

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Hot Take:

Who knew that converting spreadsheets could be as thrilling as a James Bond movie? It turns out, those old-school .xls files are hiding some seriously outdated security tricks that get dragged into the modern world of .xlsx. Spreadsheets are like cats—they never forget!

Key Points:

  • Older .xls files use a simple 16-bit hash for protection.
  • Newer .xlsx files use a robust SHA256-based hash.
  • Converting .xls to .xlsx carries over the 16-bit hash.
  • This creates a potential security risk in the converted file.
  • Awareness of this issue is crucial for data security.

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