How to Remove Embedded Attachments from PDFs

PDFs can contain hidden attachments that you might not know exist. Before sharing documents, it's important to check for and remove any embedded files.

What Are PDF Attachments?

PDF attachments are files embedded within a PDF document. They can include:

• Source documents (Word, Excel files)
• Supporting images
• Data files
• Other PDFs
• Any file type

Unlike linked files, attachments travel with the PDF—anyone with the document has access to the attached files.

Why Attachments Are a Risk

Hidden from View

Attachments may not be immediately visible:

• Displayed only in attachment panels
• Not shown in page content
• Easy to overlook before sharing

Can Contain Sensitive Data

Attachments might include:

• Original documents with more information than the PDF
• Source files with tracked changes
• Confidential supporting materials
• Files you didn't intend to share

Security Vulnerabilities

Attachments can potentially contain:

• Malware (though most readers block execution)
• Sensitive macros
• Scripts

How to Find Attachments

In Adobe Acrobat/Reader

1. Look for a paperclip icon in the left panel
2. Or go to View > Show/Hide > Navigation Panes > Attachments
3. The Attachments panel shows all embedded files

In Other PDF Readers

Most readers have an attachments panel or similar feature:

• Foxit: View > Navigation Panels > Attachments
• Preview (Mac): View > Show Markup Toolbar, then check for attachments
• PDF-XChange: View > Panes > Attachments

Programmatically

Using command-line tools:

# Using pdfdetach (poppler-utils)
pdfdetach -list document.pdf

How to Remove Attachments

Method 1: Adobe Acrobat Pro

1. Open the Attachments panel
2. Select the attachment(s) to remove
3. Click the Delete button (trash icon)
4. Save the document

Method 2: Sanitization Tools

CleanPDF and similar tools remove attachments as part of sanitization:

1. Upload to CleanPDF Sanitize
2. The sanitization process removes all attachments
3. Download the clean file

Method 3: Command Line

Using poppler-utils:

# List attachments
pdfdetach -list input.pdf

# Save without attachments requires recreating the PDF
# Use Ghostscript or QPDF for this

Method 4: Re-export

1. Print to PDF (creates a new file without attachments)
2. Or use "Export" rather than "Save" in some applications

Types of Embedded Content

File Attachments

Actual files embedded in the PDF. Most visible type.

Embedded Files

Similar to attachments but may be referenced by form actions or scripts.

Portfolio Files

PDF Portfolios can contain multiple files in a single PDF package.

Embedded Fonts

Not typically a security concern, but can be large.

Embedded Multimedia

Audio, video, or 3D content embedded in PDFs.

When to Check for Attachments

Before Sharing Externally

Always check documents before sending outside your organization.

When Receiving PDFs

Inspect incoming PDFs for unexpected attachments.

When Sanitizing for Compliance

GDPR and other regulations may require removing attachments with personal data.

Before Publishing

Documents published publicly should be checked thoroughly.

Risks of Not Removing Attachments

Case 1: Source Document Exposure

A PDF exported from Word might include the original Word file as an attachment, complete with:

• Tracked changes showing all edits
• Comments from reviewers
• Previous document versions

Case 2: Accidental Data Sharing

A report PDF might have a supporting Excel file attached that contains:

• More data than shown in the PDF
• Formulas revealing calculation methods
• Raw data not meant for distribution

Case 3: Legacy Attachments

A document passed between many people might accumulate attachments that no one remembers adding.

Best Practices

For Document Creators

1. Check before finalizing - Review attachments before sharing
2. Remove unnecessary files - Only keep essential attachments
3. Consider security - Are attachments appropriate for all recipients?

For Document Receivers

1. Check incoming PDFs - Be aware of what's attached
2. Scan attachments - If opening, ensure they're safe
3. Don't forward blindly - Check before redistributing

For Organizations

1. Include in workflows - Make attachment checking standard
2. Use sanitization tools - Automate removal for sensitive documents
3. Train staff - Ensure awareness of attachment risks

Verification After Removal

After removing attachments:

1. Check the Attachments panel - Should be empty
2. File size comparison - Should be smaller if large files were removed
3. Test the document - Ensure nothing broke
4. Use analysis tools - Verify complete removal

The Sanitization Advantage

While you can manually remove attachments, sanitization tools like CleanPDF offer advantages:

• Comprehensive - Removes all types of embedded content
• Also removes - Metadata, comments, revision history
• Quick - One step instead of manual checking
• Reliable - Consistent results

Conclusion

PDF attachments are easy to overlook but can pose significant privacy and security risks:

1. Always check - Before sharing any important document
2. Remove unnecessary attachments - Only keep what's needed
3. Consider sanitization - For comprehensive cleanup
4. Verify removal - Confirm attachments are gone

Taking a few moments to check for attachments can prevent embarrassing or harmful information leaks.

Need to remove attachments and other hidden data from a PDF? Use CleanPDF's Sanitize tool for comprehensive cleanup.