HackBlue

Labs / Hashes and verification

Same rows, different hash

Finance’s vendor file does not match the hash the bank sent, so someone suspects tampering. Compare the bytes and show that line endings, not edits, changed the hash.

  • Terminal mission
  • Intermediate
  • 4 objectives
  • 0 of 4 solved

Briefing

Before every payment run the bank emails a SHA-256 of the vendor master file it holds. Today the hash of vendors.csv on the finance share does not match, and the payment run is on hold.

A hash covers every byte, including invisible ones. Windows ends lines with CR LF (0d 0a) and Linux with LF (0a). A file opened and saved on the other kind of system can change every line without changing a single visible character.

analyst@fin-share

fin-share · Hashes and verification

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