Excel Password Recovery. The Possible And The Unbelievable

I’ve been developing password recovery software since 1999, and I can tell you that some time or another everybody loses a password: regular users, corporate clients, and even military and government employees.

The nice thing about Excel files is that losing your password isn’t always a huge headache.

Microsoft Excel files use various types of password protection to limit access to spreadsheet data. Some types of protection use weak algorithms – those passwords can be recovered or deleted instantly. Other types of Excel password protection use strong algorithms, and it takes serious computer resources to crack them.

If you’d like to know a little bit more about when a lost Excel password is no big deal and when you’re going to have to bring out the big guns, keep reading.

Instant Recovery or Deletion of Excel Passwords

The following types of Excel passwords can be recovered or deleted instantly:

• Excel VBA macros password
• Password to modify
• Sheet and workbook passwords

Excel password protection falls into two types – passwords to open files and additional passwords that protect specific data inside a spreadsheet.

Those additional passwords are so weak that they can be recovered or deleted instantly. There are lots of programs out there that can handle the job.

All it takes is a couple of small tricks to get rid of this kind of password.

For example, in newer versions of Microsoft Office, the Excel VBA password can be changed to a known password or simply deleted.

Sheet passwords can’t be recovered. Instead, what you do is find colliding passwords analogous to the original passwords. This lets you remove protection from the Excel sheets and regain access to your data.

Basically, additional passwords to Excel spreadsheets can be dealt with instantly (either deleted or recovered) for files created in any version of the software, from Office 6-95 to Office 2013.

Password to Open Excel 6-95 Spreadsheet. Instant Recovery

In Excel 6-95, Microsoft used its usual password protection technology. That was a mistake. Specialized programs quickly appeared that could crack Excel 6-95 passwords instantly while the file was opening.

Password to Open Excel 97-2003. File Decryption

Things changed when Excel 97 was released. Now Excel was using real cryptographic algorithms (RC4 together with the MD5 hash algorithm). But even this new protection turned out to be insufficient.

It was soon discovered that you didn’t have to actually recover the password to regain access to the data!

It became a lot easier to simply decrypt the file by finding the key used to encrypt it in the first place (one such program is Accent OFFICE Password Recovery).

An even faster option leverages the power of rainbow tables to recover the key from a pre-existing key database and encrypt the protected file (such as with the AccessBack.com service).

Both key recovery and rainbow tables deliver the same result: an exact copy of the original Excel spreadsheet in next to no time.

Password to Open Excel 2007-2013 Spreadsheets. GPU Computing

Microsoft once again changed its encryption scheme with the release of Office 2007. Now Excel was using really serious technology to safeguard files.

But there were still ways to get around it.

One obvious way to recover these new, hard-to-crack passwords is to use software that can automatically try all possible options. Because this can take a long time, you want to use a program that has smart tools for manipulating the range of passwords tested.

And developers soon discovered that they could speed up the process further by using the processing power of graphics cards!

Graphics cards get more and more power each year, making them the perfect choice for recovering the passwords used in newer Microsoft Office files. When you have several hundred GPU parallel processors all searching for the same password, you get results many times faster than you would using even the most advanced processor.

So if you need to recover passwords to open Excel 2007-2013 spreadsheets, using NVIDIA – or even better, AMD – graphics cards can make a huge difference.

Choosing Tools

A quick online search will turn up lots of different programs for recovering passwords. Some of them are terrific, others are just junk. What should you do if you want to save time and make the right choice?

I’ve put together a checklist of features that any good password recovery program should have:

• Support for all versions of Microsoft Excel
• Optimized source code for high speed
• Instant recover of the additional passwords used in Excel
• Support for AMD and NVIDIA graphics cards
• Multiple types of attack for hard-to-crack passwords
• Flexible password search parameters
• Flexible management of the range of passwords tested
• Support for command line interface

When you’re considering a password recovery program, read through all the specs and check off the features on the list above. You’ll be glad you took the time to choose the right software once you get down to recovering your password.

Here’s a video tutorial with examples of how one password recovery program handles Excel passwords:

Summary

Here’s what you’ve learned:

With Excel, the only passwords that are really hard to crack are the passwords to open Microsoft Excel 2007-2010-2013 files.

Recovering these passwords takes time and computing power (and it helps if you have at least some idea of the password’s structure).

If you’ve lost any other type of Excel password and can’t access your data, there’s nothing to worry about. All of the other passwords are easy to recovery.

Resources

Accent OFFICE Password Recovery — fast recovery of any Microsoft Office passwords (CPU and GPU).

AccessBack.com — online service offering guaranteed decryption of Excel and Word 97-2003 files.

GPU Rating — this nice little table shows you how fast various graphics cards are at recovering passwords.