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Consider an Excel file and the following sequence of events.

  1. Input "SecretPW" into A1 cell.
  2. Save the file.
  3. Change contents of A1 to "AnotherPW".
  4. Send the file to somebody over the internet.

Question: Is it possible in any way (even say theoretical or based on probability) to recover the previous content of the A1 cell (i.e. the "SecretPW")?

If yes, then do you have any idea how:) ?

Thank you guys!

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4 Answers 4

up vote 1 down vote accepted

Yes, deleted data can still be stored in the file & recovered by a 3rd party to whom you send the file. Most word processing and spreadsheet programs preserve deleted data for some time; this data is part of what's usually called "metadata" -- data you don't see. This is true even if you are not tracking revision history; this is the data that is used, for example, when you "undo" an edit.

One way to remove metadata is to convert the file to another format and back again, as Al Everett suggests.

This is a detailed explanation from MS about metadata in Excel, but it is a bit dated: http://support.microsoft.com/default.aspx?scid=kb;EN-US;223789 . The concepts still apply to later versions.

In Excel 2007, you can use the "Document Inspector" feature to clean up metadata. There are details on what this feature does at http://office.microsoft.com/en-us/excel-help/remove-hidden-data-and-personal-information-from-office-documents-HA010037593.aspx#BM1

Usually, the easiest thing to do to remove just revision-related metadata (i.e. deletions as you mention) is to just save the file using "Save As", to a new name, and use XLS format if you currently use XLSX. This -should- remove all the revision metadata but will not remove other items like your name etc.

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Is it possible to retrieve this information using some sort of existing software tool? –  NeverStopLearning Oct 8 '13 at 12:36
    
It's very easy to see some metadata just by opening the Excel file with a text editor. I haven't ever deliberately searched for "undo" information, but in the past, I've found it easy to find the licensee name info, font info, etc. There were some news stories a few years ago about MS Office files that were distributed without removing the metadata, allowing the wrong people to see sensitive information. As I have consulted for lawyers, I'd point to a document such as americanbar.org/content/dam/aba/administrative/… –  Debra Oct 9 '13 at 6:39

It is impossible to recover old information from third party. You can send that file to anyone its fine don't worry about your personal information.

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Okay, thanks. I will wait a while if somebody else doesnt come-up with a solution and then I will accept your answer. –  NeverStopLearning Mar 28 '13 at 6:45

In Office programs there is a feature to record changes. If this feature is enabled it is possible to review all the changes made to a document.

Tracking changes in Excel 2007

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Yes I know, but this is not what I had in mind, sorry. I am considering a security of simple cell contents wipe before sending the file to "hostile" zone. And I dont want them to recover what was deleted in any way. –  NeverStopLearning Mar 27 '13 at 22:08

Its impossible to know what Microsoft does with old info. If you are worried then make a copy of the data to a new file. You could do this via an innocuous file type such as CSV, nothing could then be saved which you cannot see, and put the data back into Excel later.

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