PDF Viewer security for server side and web assebembly

[Eimantas Baigys]

How secure is PDF viewer is user upload infected PDF file with malicious malware, phishing, or exploits. 

things like: Redirect to phishing websites, Open hidden links, attempt browser-based exploits, collect system info, malicious JS triggered during viewing, embed .exe, .js, .vbs, .jar, .ps1 files, embedded scripts disguised as images, PNG/JPG “images” containing malicious payloads (steganography or trick injection), small script that extracts a hidden payload into a temp directory and runs it, buffer overflow vulnerabilities, corrupted object streams, 

JBIG2 / font exploits, remote file inclusion, password-protected PDF attacks (like uploading encrypted PDFs that they cannot be scanned.

and others?

[Venkada Subramanian Durai]

Hi Eimantas Baigys,

Thank you for the update. PDFs can contain malicious content such as embedded scripts, phishing links, or corrupted streams. Here’s how our viewer handles these concerns:

 

• No JavaScript Execution: The viewer does not execute JavaScript embedded in PDFs, preventing script-based attacks.
• Links Behavior: As of now, we cannot predict or control whether links inside a PDF are safe. From the PDF library, we only parse objects present in the PDF. We do not execute links or perform security checks on them.
• Sanitization: We sanitize the text during processing to prevent script injection. However, if malicious content exists at the document creation level (e.g., embedded executables or payloads), it is not handled by the viewer.
• Rendering Environment:
  • Server-side rendering: Files are processed on the server, reducing client-side exploit risk.
  • WebAssembly rendering: Runs in a sandboxed environment, limiting access to system resources.

 

What the viewer does not do:

• It does not decrypt password-protected PDFs for scanning.
• It does not guarantee protection against zero-day exploits or hidden payloads.

 

Recommended Best Practices:

• Scan uploaded files with antivirus/malware tools before rendering.
• Apply file validation and size/type restrictions.
• Keep Syncfusion libraries updated for security patches.
• Consider sandboxing or containerization for file processing.

 

While the viewer mitigates many risks, full security requires combining it with server-side scanning and strict upload policies.

Regards,
Venkada Subramanian D