Metadata in Office files

Risks of Office metadata

Office documents are a difficult format for anonymity.

Word, Excel, and PowerPoint can retain author information, change history, comments, hidden sheets, templates, internal paths, and collaborative editing information. Even if you think you removed something visually, the work process may remain inside.

This article organizes the risks of Office metadata. A discussion focused on author information is handled in "Author information in Office files."

What is Office metadata?

Office metadata is information attached to a document other than the body text.

Office files are suited for editing and collaboration.

For that reason, when treating them as publication files, internal information needs to be checked.

Easy-to-miss items in Excel and PowerPoint

Pay attention not only to Word, but also to Excel and PowerPoint.

Excel may retain hidden sheets, filters, cell comments, defined names, and external links. PowerPoint may retain presenter notes, hidden slides, original image information, and comments.

Checking only the visible page is not enough.

You need to use the application's document inspection feature and recheck after conversion to another format.

Be careful with sharing methods

Office files are often combined with cloud sharing.

Even if metadata in the file itself is removed, the sharing link's owner name, editing history, access permissions, and information contained in the URL may remain.

For anonymity, check not only the file, but also the sharing route.

Flow for making a publication file

When making an Office document ready for publication, separate the editing file from the publication file.

The editing file may need history and comments. But if it is published as-is, the creation process and people involved become visible.

Creating a publication copy lets you preserve evidentiary value and work history while reducing the information released outside.

In whistleblowing and legal consultation, how to store the original file is also important.

Situations where you should not hand over an Office file as-is

In situations where anonymity is important, there are cases where you should not hand over an Office file as-is.

Especially in whistleblowing, workplace trouble, school issues, and source protection, author information and editing history can narrow the people involved.

Office documents are good at retaining traces of collaboration.

This is convenient for work, but dangerous for anonymous publication. Information about who changed what, when, and where can become a stronger clue than the content itself.

Handling documents you receive

Pay attention not only to Office documents you created, but also to documents received from others.

In whistleblowing, reporting, and consultation, you may receive documents created by a provider. Those documents may contain information about the provider, colleagues, organization, device, or cloud.

Documents you receive often contain information the person themselves did not notice.

Before publishing or sharing, always check with a separate copy.

Do not stop at document inspection

Office includes features for checking personal information and hidden information inside documents.

This is useful, but it cannot be entrusted with all anonymity checking. Information found by document inspection and information readers infer from the text or tables are separate. Internal terms, case names, abbreviations used only by a department, table ordering, and text inside images can be difficult to judge through mechanical inspection alone.

For anonymous publication, combine tool checking with human reading.

Do not think "it is safe because I removed it with a feature." Reread the final document to be published from the recipient's perspective.

Summary

Office metadata may include author, company name, change history, comments, hidden sheets, presenter notes, links, and collaborative editing information.

For anonymity, the basic rule is not to publish Office files as-is.

Create a publication copy and check document inspection, hidden information, comments, links, filenames, and sharing destinations.

Even if you convert to PDF, metadata checking after conversion is necessary.

Office documents are a format that may hand over not only the body text, but also the work environment.

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