Skip to main content

Breaking Excel password protection

If you came across an excel sheet asking for password for allowing to make any changes into it, you may want to unprotect it.
All we need to do is to edit the xml file which comes intrinsically packaged with Excel 2007 or 2010. But what about Excel 2003? For that, open the Excel 2003 file within Excel 2007, save it as xlsx file. So, keep in mind all the Excel files below 2007 version, you need to convert them as Excel 2007 with extension .xlsx.
Now here are the steps for doing that:
1. Open the Excel 2003 file (e.g. Secret.xlsx) and save it as .xlsx (Excel 2007) format. If you already have Excel 2007 file, then no need for any conversion.

2. Now change the extension of the above file to .zip and extract the zipped file. Browse through the file in the extracted folder and go to:
<LocalPath>\Secret\xl\worksheets.
 
3. Now open the sheet/ sheets you want to remove protection in any xml editor. Look for keywords such as 'sheetProtection' or 'workbookProtection' in the xml file.
Remove such lines entirely from the xml files above. Do this for all the sheets you want to remove the protection.

4. Now, copy all these edited and saved xml files to the original zip file under the same path. Now change the extension back to .xlsx from .zip. You are done!

Comments

Anonymous said…
I tried your suggestion. But it did not work. After saving it as an xlsx file, I rename the file to a zip extenstion.

That is where I start having a problem. The file fails to extract stating its an invalid file.
Nilesh Kumar said…
@ Anonymous,
Seems you file is an Excel 2003 file.
As I have mentioned in the blog, this only works for Excel 2007 or 2010 with .xlsx extension. If the file is Excel 2003, you need to open it with Excel 2007 and save it with .xlsx extension.So, keep in mind all the Excel files below 2007 version, you need to convert them as Excel 2007 with extension .xlsx.
Let me know if that helps.
Thanks,
Nilesh
Anonymous said…
How can you open a password protected Excel 2003 file with Excel 2007 and save it with .xlsx???? If a file has a password, you can't open it!!!!!!!!
shekhar said…
i have a file in excel 2007 password protected i cant open beacuse forget password i am very thankful if u help me in open i send u a file on your email id

regards
shekhar
Anonymous said…
Dear I have an excel 2003 sheet which is password protected and I can not open it. I have tried the brute forcing software but it takes hell lot of time. is there some simple way to remove the password
Anonymous said…
That worked very well. Hard to believe that the "protection" was that easy to crack. Why in the heck would anyone use a code cracker to try and guess the password when this method took me all of 10 minutes from start to finish, and that includes the time it took to download a zip file program? Thanks for the tip.
FGSouza said…
The method works to unprotect a spreadsheet. However how can I, (after have unprotected the sheet and made my modifications), return the protection with the same password that was before? Any ideas?
Abhishek said…
Thanks a lot Nilesh. I tried and it worked.
Anonymous said…
didn't work for me. Is there a 2006 version of Excel? I think that's what mine is
RenĂ© Jensen said…
Works fine
Can you get the password to?

Popular posts from this blog

Ardilla- New tool for finding SQL Injection and XSS

Three Researchers -- MIT's Adam Kiezun , Stanford's Philip Guo , and Syracuse University's Karthick Jayaraman -- has developed a new tool ' Ardilla ' that automatically finds and exploits SQL injection and cross-site scripting vulnerabilities in Web applications. It creates inputs that pinpoint bugs in Web applications and then generates SQL injection and XSS attacks. But for now Ardilla is for PHP -based Web app only. The researchers say Ardilla found 68 never-before found vulnerabilities in five different PHP applications using the tool -- 23 SQL injection and 45 XSS flaws. More information is awaited. For their attack generation techniques refer to their document at: http://www.cs.washington.edu/homes/mernst/pubs/create-attacks-tr054.pdf

Combining power of Fiddler with Burp

Both are pretty powerful tools when it comes to intercept and modify http communications. But at some point of time, they become even more powerful combo if tied with each other. They complement each other. In a recent pentest I came across a similar situation where in Burp was not able to intercept a specific kind of traffic and Fiddler came to rescue. The application was designed to upload video. The initial communication was straight forward, I mean logging into application, filling up the video details etc. And all these were easily captured by Burp except the point where you hit the Upload Video and it connects to a different server and surprisingly it was not captured by Burp, not sure why, even after repeated attempts. So, I fired Fiddler to see if the it sees this request. But it's a;ways to play with requests using Burp due to it's various functionalities like, Intruder, Repeaters etc. But it was necessary to capture this request in Burp. So the below steps can be

File Upload through Null Byte Injection

Sometimes, during file upload we come across situation wherein there would be check on the file extension at the client side as well as server side too. If the application does allow only .jpeg extension to be uploaded, the client side java script checks for the extension of the file before passing the request. We all know that how easily this can be defeated. Some applications, checks for the extension at the server side also. That's not easy to bypass. However there are some ways with which it still can be bypassed. Most of server side scripts are written in high level languages such as Php, Java etc who still use some C/C++ libraries to read the file name and contents. That leads to the problem. In C/C++ a line ends with /00 or which is called Null Byte. So whenever the interpreter sees a null byte at the end of the a string, it stops reading thinking it has reached at the end of the string. This can be used for the bypass. It works for many servers, specially php servers. T