How Secure is A Password Protected Excel File?

/ Posted by Shirley Howard to Excel / Follow @Shirley Howard

Be it any kind of data, it is inevitable that each and every file you have should be protected so that you are headache free of any misuse or data loss. When it comes to Excel files, it is not an exception! Excel is used by many people daily to store and evaluate sensitive data and they are aware of the same. And this is where there is an absolute need to password protect Excel file and prevent tampering. But the main question that arises here is “How secure is a password protected Excel file?” and we are here to help you find the answer here.

Part 1: How Secure are Excel Password Protected Files?

If you are wondering how safe is Excel password protection? The answer is it is not full-proof! With the in-built password protection of Excel files, we can say there is good amount of protection but nothing that strong which can save you from something severe.

Though Microsoft has thrown in quite a lot of effort over the years to make it stronger and more secure using different encryption algorithms. Microsoft has made the level of protection strong and if you lose the password, the file will be useless.

The encryption used in Excel 97 to 2003 (.xls) for legacy files are RC4 as compared to more secure AES in Open XML files used after 2007 for example (.xlsm, .xlsb, .xlsx etc). A fun fact here is that Excel doesn’t save a password as an input rather it stores a string of data which is commonly known as Hash. And this is the Hash algorithm you see whenever you generate a password under an XML code. These hashes are small and can be any number or even character.

But this hash implementation can also unlock your protected Excel file because it can be hacked by combinations or by Brute-Force attacking programs. This is mainly because they are short. The hacking program can easily cycle through a limited number of combinations.

But after the release of 2013 Excel version, Microsoft has made slight tweaks to the encryption and that has made a lot of difference. What they have done is that they have just increased the hash length with more complex numbers and letters. This complexity leads to a difficulty of finding the right combination and eventually gets you a very unique password.

So, the first tip here is to save your files from “.xls” file to “.xlsx” file.

  • Upgrade Excel to at least to 2007 version if not 2013 or else you are highly compromising security.
  • Choose unique, random and complex passwords following good password policies.
  • Save the file on a good location preferably on an encrypted hard disk.
  • Password protect your files, workbooks, worksheets, all cells, or each cell for added protection.  You can do that by protecting your workbook and protecting your sheets.

Part 2. How to Secure An Excel File?

1. Use Document Open Password in Excel 2013 and above:

If you want to protect an Excel workbook, so that no one other than you can open the workbook, apply a Document Open Password. Follow the steps below:

  • Launch the required Excel workbook.
  • Tap on File and then again tap on Info.
  • Now, find and tap on “Protect Workbook” and then click on “Encrypt with Password”.
  • encrypt document open password
  • Put a new random password as discussed earlier and then re-enter again and just tap on “OK”
  • enter password and confirm
  • Now just tap "Save" to save changes.

2. Use Modify Password:

Modify password is basically an added layer of protection. It prevents other users to open, change or modify your protected Excel workbook. If someone wants open this Excel file, he or she will be asked to enter the modify password to open the workbook. If they don’t have this password, he or she will be able to open the document as Read-Only. Here’s how to apply this on your workbook:

  • On your Excel workbook, go to "Save As" and select the location for storage.
  • Now, find “Tools” inside the window and then go “General Options”.
  • general options excel
  • Now, just put in a password inside the “Password to modify” option and tap “OK”. Again, re-enter the password and tap “OK”.
  • enter modify password excel
  • Tap “Save” to save changes.

3. Use Structure Password:

If you have a Structure password on your workbook, you basically protect your file from other people so that they can’t modify your sheet and that includes adding, deleting, renaming, hiding worksheets etc. So if somebody wants to do all this, he or she will have to unprotect the workbook with the original Structure password first. Here’s how to apply:

  • Go to your Excel workbook and find “Review” from the taskbar and then tap on “Protect Workbook”
  • protect workbook
  • You will get a “Protect Structure and Windows” box where you need to type a unique password and then tap “OK”.
  • enter structure password
  • Again renter the same password and press “OK” and save the changes.

4. Use Password for Worksheet:

If you protect your worksheet with a password, it can basically help you protect all the data on your sheet. This can work great if you want to prevent anyone from tampering your worksheet cells. Here’s how to do it:

  • Similarly, open Excel workbook, tap on “Review” and then go to “Protect Sheet”
  • protect Excel sheet
  • Put in a new password for worksheet and tap “OK”. Reenter and again tap “OK”
  • protect Excel sheet
  • Tap Ctrl + S to save.

Is Excel password protection secure?” All of you, some way or the other had this question in mind; the answer to this depends on how you work on it. Follow the steps above to take your protection up a notch.

Bonus Tip: How to Save a Protected Excel File as Unprotected?

You can easily save a protected Excel file as unprotected by using a professional unlock tool like PassFab Excel Password Recovery. This is by far the best way to save a password protected Excel file as unprotected. It will basically recover or unprotect your Excel file and then you can save it to whichever location you want. It is the quickest solution out there and supports all Excel versions. It is also very fast and extremely easy to use thanks to its user-friendly interface. Here’s how to use PassFab Excel Password Recovery:

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  • First download and install the program from the official website. Online options are also available.
  • Now, run Excel Password Recovery on your desktop. You will see the main interface now.
  • main interface PassFab excel password recovery
  • Tap on “Add” to upload Excel file for decryption
  • add file password recovery
  • There are 3 decryption methods available based on your circumstances.
    • Dictionary Attack (Quick but needs password dictionary)
    • Brute-force Attack (Default but takes sometime)
    • Brute-force with Mask Attack (Fast but needs your input)
  • The default option here is Brute-force attack and it often does the job well enough.
  • Tap on “Start” after selecting your desired decryption method.
  • find password

Now the program will start decrypting the password-locked file. Wait for some time, and the password will be showcased with a popup alert. The time for decryption usually depends on the complexity of passwords. So, make sure you choose the right decryption method.

Bottom Line

So, are password protected Excel files secure? In this article, we have given a detailed idea of how secure Excel password protection is and some step by step tips on how to protect your Excel workbook by password protection. Make sure, you try these tips one by one, so as to understand the functionality and effectiveness of each one of them. As we said, passwords are not the sure shot way to protect your Excel files but nonetheless, it acts as a good buffer to hackers or people who want to change/modify/ tamper with your workbook. Try to use the latest version of Excel for added benefits. And to finish off, we highly recommend you to go for PassFab Excel Password Recovery tool to save protected Excel files as unprotected easily and efficiently.

Free Try PassFab Excel Password Recovery Now:
Free Download For Win 10/8.1/8/7/XP
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