Building a Custom Digital File Upload and Virus Scanning Middleware for Messaging

How-To-Articles
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Building a Custom Digital File Upload and Virus Scanning Middleware for Messaging

What This Guide Covers

This masterclass details the construction of a secure File Upload Pipeline for digital messaging channels (Web Messaging, SMS, Social). By the end of this guide, you will be able to architect a middleware layer that intercepts customer attachments, scans them for viruses using a cloud-native engine (like ClamAV or AWS GuardDuty), and only delivers the “Clean” files to the Genesys Cloud agent workspace. This is a critical security requirement for organizations handling sensitive documents (e.g., insurance claims, medical records, or identity verification).

Prerequisites, Roles & Licensing

Implementing secure file handling requires custom middleware development and cloud security configuration.

  • Licensing: Genesys Cloud CX 1, 2, or 3.
  • Permissions:
    • Messaging > Integration > View/Edit
    • Integrations > Custom Connector > View/Add
  • OAuth Scopes: messaging, integrations.
  • Infrastructure: A compute layer (AWS Lambda, Azure Functions) and a storage/scanning layer (S3 + ClamAV or similar).

The Implementation Deep-Dive

1. The “Open Messaging” Architecture for File Interception

While native messaging handles attachments automatically, a secure pipeline requires you to sit “in the middle.” Using the Open Messaging API allows you to receive the file before Genesys Cloud does.

Architectural Reasoning:
By intercepting the file at your middleware endpoint, you prevent potentially malicious payloads from ever reaching the Genesys Cloud infrastructure or the agent’s local browser cache.

2. Designing the Scanning Workflow

When a user sends an attachment via your digital channel:

  1. Upload: Your middleware receives the binary data or a public URL from the source (e.g., WhatsApp).
  2. Quarantine: The file is saved to an isolated “Quarantine” bucket in your cloud environment.
  3. Scan: An automated trigger (S3 Event Bridge) launches a virus scanning container.
  4. Decision:
    • CLEAN: Move the file to a “Safe” bucket and generate a short-lived Pre-Signed URL.
    • INFECTED: Delete the file and trigger an automated response to the customer: “Your attachment failed our security check.”

3. Delivering the “Clean” File to Genesys Cloud

Once the file is verified, you pass the Pre-Signed URL to Genesys Cloud via the Open Messaging API.

Implementation Step:
Construct the inbound message payload including the content array with an attachment object.

{
  "content": [
    {
      "contentType": "Attachment",
      "attachment": {
        "url": "https://safe-bucket.s3.amazonaws.com/clean-doc.pdf?X-Amz-Signature=...",
        "filename": "customer_document.pdf",
        "mediaType": "application/pdf"
      }
    }
  ]
}

4. Implementing Agent-Side Security Policies

Even with scanning, you should enforce least-privilege for agents handling attachments.

The Trap:
Allowing agents to download files to their local machine.
The Solution: Use Genesys Cloud Media Policies to restrict “Download” permissions. Force agents to view the attachment within the In-App Document Viewer. This prevents sensitive data from being saved to unmanaged agent desktops.

Validation, Edge Cases & Troubleshooting

Edge Case 1: Scanning Latency vs. Customer UX

  • The failure condition: A customer sends a 50MB file, and the scanning takes 30 seconds. The agent is waiting, and the customer is confused.
  • The root cause: Synchronous scanning of large files.
  • The solution: Implement Asynchronous “Scanning” Placeholders. Immediately deliver a message to the agent: “[System: Scanning Attachment…]”. Once the scan is complete, use the Message Update API or send a second message with the actual file link.

Edge Case 2: Multi-Part/Form-Data Parsing

  • The failure condition: Your middleware fails to parse the file because it’s sent as a multipart/form-data stream instead of a raw binary.
  • The root cause: Inconsistent formatting from different social media providers.
  • The solution: Use a robust parsing library (e.g., Busboy for Node.js) and ensure your middleware handles both raw binary and base64-encoded payloads.

Official References