How to Sanitize PDF in C# with IronPDF

Quickstart: PDF Sanitization with IronPDF

Enhance the security of your PDF documents using IronPDF's Cleaner class. This quickstart guide demonstrates how to sanitize a PDF in C# .NET with minimal code. By leveraging the ScanPdf method, you can remove vulnerabilities like embedded scripts and metadata, ensuring your PDFs' integrity and security. Follow the code snippet to clean your PDF and protect against potential threats.

How Do I Sanitize a PDF?

PDF sanitization works by converting the PDF document into an image format, which removes JavaScript code, embedded objects, and buttons, then converting it back to a PDF document. We provide Bitmap and SVG image types. This approach is particularly useful when dealing with PDFs from untrusted sources or when preparing documents for secure deployment on cloud platforms like Azure or AWS Lambda. The key differences of SVG from Bitmap are:

• Quicker than sanitizing with bitmap
• Results in a searchable PDF
• Layout might be inconsistent

:path=/static-assets/pdf/content-code-examples/how-to/sanitize-pdf-sanitize-pdf.cs

using IronPdf;

// Import PDF document
PdfDocument pdf = PdfDocument.FromFile("sample.pdf");

// Sanitize with Bitmap
PdfDocument sanitizeWithBitmap = Cleaner.SanitizeWithBitmap(pdf);

// Sanitize with SVG
PdfDocument sanitizeWithSvg = Cleaner.SanitizeWithSvg(pdf);

// Export PDFs
sanitizeWithBitmap.SaveAs("sanitizeWithBitmap.pdf");
sanitizeWithSvg.SaveAs("sanitizeWithSvg.pdf");

When choosing between bitmap and SVG sanitization, consider your specific requirements. SVG sanitization maintains text searchability, making it ideal for documents that need to remain searchable after sanitization. This is especially important when working with extracted text from PDFs or when implementing PDF accessibility features like PDF/UA.

:path=/static-assets/pdf/content-code-examples/how-to/santize-pdf-sanitize-chrome-render-options.cs

using IronPdf;

// Customize Chrome render options
var options = new ChromePdfRenderOptions();

// Set bottom margin to 50 pixels
options.MarginBottom = 50;

// Import PDF document
PdfDocument pdf = PdfDocument.FromFile("sample.pdf");

// Sanitize with Bitmap with Chrome render options
PdfDocument sanitizeWithBitmap = Cleaner.SanitizeWithBitmap(pdf, options);

// Sanitize with SVG with Chrome render options
PdfDocument sanitizeWithSvg = Cleaner.SanitizeWithSvg(pdf, options);

// Export PDFs
sanitizeWithBitmap.SaveAs("sanitizeWithBitmap.pdf");
sanitizeWithSvg.SaveAs("sanitizeWithSvg.pdf");

How Do I Scan a PDF for Vulnerabilities?

Use the ScanPdf method of the Cleaner class to check if the PDF has any potential vulnerabilities. This method checks with the default YARA file. However, you can upload a custom YARA file that meets your requirements to the second parameter of the method. This scanning capability is essential for maintaining document security, especially when working with PDFs that may contain embedded attachments or form fields.

A YARA file for PDF documents contains rules or patterns used to identify characteristics associated with malicious PDF files. These rules help security analysts automate the detection of potential threats and take appropriate actions to mitigate risks. YARA is particularly effective at detecting:

• Embedded JavaScript exploits
• Suspicious form actions
• Hidden malicious content
• Known vulnerability patterns
• Unauthorized embedded files or streams

:path=/static-assets/pdf/content-code-examples/how-to/sanitize-pdf-scan-pdf.cs

using IronPdf;
using System;

// Import PDF document
PdfDocument pdf = PdfDocument.FromFile("sample.pdf");

// Scan PDF
CleanerScanResult result = Cleaner.ScanPdf(pdf);

// Output the result
Console.WriteLine(result.IsDetected);
Console.WriteLine(result.Risks.Count);

:path=/static-assets/pdf/content-code-examples/how-to/sanitize-pdf-custom-yara.cs

// THIS CODE SNIPPET IS NOT AVAILABLE!

Best Practices for PDF Sanitization

When implementing PDF sanitization in your applications, consider these best practices:

1. Always Scan Before Processing: Run vulnerability scans on all incoming PDFs, especially those from external sources or user uploads.

2. Choose the Right Sanitization Method: Use SVG sanitization when text searchability is important; use bitmap sanitization for maximum security when dealing with highly sensitive documents.

3. Preserve Original Files: Keep copies of original PDFs before sanitization for audit trails or recovery purposes.

4. Implement Logging: Track all sanitization operations for security audits and compliance requirements.

5. Regular Updates: Keep your YARA rules updated to detect the latest PDF-based threats and vulnerabilities.

PDF sanitization is just one aspect of comprehensive PDF security. For additional security measures, explore setting PDF passwords and permissions or implementing digital signatures to ensure document authenticity and integrity.

Ready to see what else you can do? Check out our tutorial page here: Sign and Secure PDFs