Removing metadata from files¶

The problem with Windows’ built-in metadata removal¶

The “Remove Properties and Personal Information” feature in Windows has significant limitations that make it inadequate for proper privacy protection:

1. Limited File Format Support: Only works with 11 file formats including old Office 2003 files (DOC/XLS/PPT), JPEG, TIFF, PNG, XPS, MP3, MP4, MOV, and ASF/WMA/WMV .

2. Incomplete Metadata Removal: Even for supported formats, many metadata elements remain:

   • Office files retain editing time, template info, creation/modification dates, comments, tracked changes, and hidden content

   • Images keep most EXIF data (including thumbnails), XMP/IPTC data, and camera serial numbers

   • TIFF files appear cleaned but metadata remains recoverable with a hex editor

3. Misleading Interface: The option “Create a copy with all possible properties removed” only removes what the feature supports, not all metadata the file may contain .

Better solutions for metadata removal¶

For PDF files¶

While ExifTool can modify PDF metadata, it doesn’t permanently remove it - the original data remains recoverable . A more thorough approach involves:

1. First use ExifTool to clear metadata:

exiftool -all:all= file.pdf

2. Then use qpdf to linearize the file and remove orphaned data:

qpdf --linearize file.pdf clean_file.pdf

This combination makes the changes irreversible . However, note this doesn’t clean metadata from embedded objects within the PDF .

For Office documents¶

Microsoft Office includes a “Document Inspector” that does a decent job for single files, though it lacks batch processing capability . For batch processing Office files, third-party tools like BatchPurifier™ are recommended as they support:

• Multiple Office formats (DOCX, XLSX, PPTX)

• Removal of comments, tracked changes, hidden text, and other sensitive elements

For images and other files¶

ExifTool remains a powerful option for many file types, supporting:

• Over 60 types of hidden data/metadata removal

• Batch processing capabilities

• Support for JPEG, PNG, WebP, SVG, AVI, WAV, MP3, MP4 and more

Key recommendations¶

1. Don’t rely solely on Windows’ built-in tool - it provides a false sense of security

2. Use format-specific tools:

   • Office: Document Inspector or BatchPurifier™

   • PDF: ExifTool + qpdf combination

   • Images: ExifTool or dedicated image cleaners

3. Consider document conversion:

   • Converting to PDF via LibreOffice can remove much hidden data

   • For images, consider resaving or taking screenshots

4. Verify cleaning results - always check files after cleaning to ensure sensitive data was actually removed

The white paper from Digital Confidence provides excellent technical details about Windows’ metadata removal limitations, while ExifTool’s documentation explains its PDF handling constraints. For comprehensive cleaning, specialized tools designed specifically for privacy protection are often necessary.