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Even “100% pure data” isn’t necessarily safe. Word documents, Excel sheets, PowerPoint decks, etc. (and their Google Docs counterparts) are all suspect, because
by pmiller2 6y ago
Even “100% pure data” isn’t necessarily safe. Word documents, Excel sheets, PowerPoint decks, etc. (and their Google Docs counterparts) are all suspect, because they can contain embedded code. Some “data” formats are really not data formats at all, but code which produces the data you use (e.g. PDF, Postscript, or any Excel sheet with formulas). It’s even possible to corrupt certain otherwise inert data files in such a way as to cause malicious behavior by exploiting bugs in the software that reads them.
So, yes, while you’re technically correct that 100% inert and uncorrupted data files are safe, you have to prove that those files are not corrupted. And, so many data formats either are code or contain embedded code, so these need to be treated as suspect until proven otherwise, as well.
- bobbylarrybobby 6y agoIs there some other solution to this than to cryptographically sign 100% of the files in your system with a key that is only written down on paper?
- PeterisP 6y agoWell, yes, I would not consider arbitrary documents as "pure data" - for that I was thinking as something like a dump of a particular database table contents only, separate from all the database structure/metadata/triggers/functions/etc. You could restore a dump of pure structured data to a known clean system and that would be safe - but once you include arbitrary files as you describe, no way. Embedding malware in some periodically-accessed document on a public file share is a reasonable persistance mechanism for an attacker.
- pmiller2 6y agoI would expect a SQL dump of a database to be safe, as long as the schema only contains standard data types and no BLOBs. Once you start throwing BLOBs in there, anything goes.