Who Last Opened That File?

Category: General Weirdness | [Item URL]

Most people don't know this: Whenever you open an Excel file, your name is embedded in the file. This occurs even if you don't save the file!

Note: This behavior does not occur if the file is a read-only file.

The name that's stored is the User name listed in the Options dialog box (choose Tools - Options, then click the General tab).

A demonstration

To demonstrate, I performed the following steps:

1. I downloaded an Excel file from the Internet -- one that I have never seen before. It happened to be a file from Jon Peltier's web site.
2. I examined the Excel file using Windows Notepad. As expected, Jon's name is embedded in the file.

3. Then I opened the XLS file in Excel, and immediately closed it. I did not save the file.
4. I then examined the file again with Windows Notepad. Now, my name is contained in the file.

Although the file was clearly modified by Excel, the file modified date was not changed.

Presumably, this is how Excel keeps track of the file reservations -- but it certainly does have some "privacy" implications. A nosy employer could, potentially, see who was the last person to open the Excel files stored on a network server. So if you're snooping around in a company's Excel files, just remember to open the file as read-only if you want to cover your tracks!