Introduction to Content Disarm and Reconstruction

Content Disarm and Reconstruction (CDR) is a key concept in modern cybersecurity. It’s a process that removes hidden threats from files by tearing them down and rebuilding them safely.

If you’re familiar with typical network perimeter security workflows, you probably have a few questions after reading that first paragraph. Does CDR mean we aren’t scanning files for viruses anymore? How can we be sure files don’t contain threats just because we “rebuilt” them?

The short answer is that CDR isn’t a replacement security policy; rather, it’s more like an insurance policy which limits the likelihood of malware slipping through the cracks. We’ll explain CDR in some more detail and address all your questions in the rest of this article.

What is the role of CDR in Modern Security?

CDR is primarily employed in enterprise cybersecurity as a “defense-in-depth” strategy. It’s a zero-trust policy centered around the idea that no files entering a network can be trusted today.

Why can’t files be trusted? The simple answer: threat actors are getting ahead of the curve. It’s easier than ever for network attackers to devise entirely brand-new malware capable of fooling static signature-based antivirus protection and more dynamic, heuristic solutions alike. That’s due in part to the precipitous rise of generative AI in malware creation; motivated, sophisticated threat actors and aspiring, less-talented threat actors alike can devise effective malware at scale and launch large-scale campaigns targeting enterprise networks.

Large enterprise file entry points like email gateways, file upload portals, collaboration platforms and document management systems receive exceptionally high volume of inbound documents, and these documents disperse rapidly throughout the enterprise from their origination points. Even if a network edge antivirus solution catches 99% of the threats hidden among those files, that still means there could be hundreds of malicious files floating around in that network. The stakes are high: inadvertently executing malware from even one of those files could lead to millions of dollars in losses, and it happens all too often.

CDR acts as a first line of “cleansing” or “file sanitization” before files progress into sensitive environments from network entry points. Only the parts of the files that rigorously conform with the expectations of that file type (e.g., DOCX) are included in the new version of that document, and in some cases, the files are even flattened and converted to an entirely new format (e.g., PDF) to render potential threats inert. These rebuilt files are subsequently scanned for viruses and other threats in a typical network edge virus scanning workflow, reducing the number of possible false negatives (i.e., incorrect clean designations) considerably at the cost of additional security infrastructure.

Protection against Hidden Threats

Perhaps the greatest advantage CDR offers over a typical virus scanning workflow is hidden or zero-day threat mitigation. This is particularly true in the context of email and document-sharing systems, where large enterprises often deal with thousands of new files every day.

Phishing campaigns and embedded malware campaigns most often rely on trapping users into executing malware through some form of social engineering. CDR seeks to blindly remove the threat of execution without attempting to interpret the attacker’s guise. The benefit for users in this case cannot be understated; effective CDR technology can all but eliminate inadvertent malware execution risk for network users who might’ve been fooled by a particularly cleverly worded email subject or document title.

Comparing CDR against Direct Virus Scanning

CDR and virus scanning are not particularly similar ideas, nor are they mutually exclusive steps in an enterprise cybersecurity workflow. Nevertheless, because they have the same goal when considered independently of one another, it can be helpful to visualize a comparison between CDR and Virus Scanning workflows.

CDR with Cloudmersive

The Cloudmersive CDR API is an effective, highly scalable solution for tearing down and rebuilding incoming (or outbound) files at the network edge. It affords security administrators the option to either 1) preserve the original content format while removing its risks or 2) flatten and convert the stripped-down file to PDF to comprehensively eliminate the original threat vector. It’s designed to work seamlessly in conjunction with the Cloudmersive Virus Scan API, which offers 360-degree content verification with signature-based virus scanning and advanced zero-day threat detection.

The CDR API supports nearly 200 unique file types, including PDF, MS Office files (Word, Excel, PowerPoint, etc.) and a wide range of common image formats. It offers fast, real-time sanitization which integrates directly into existing architecture (e.g., Email servers like Exchange Online).

The CDR API can be deployed in the following models:

• Managed Instance deployments leverage dedicated, managed infrastructure with SLAs, customizable deployment, and security.
• Private Cloud deployments can take place on the customer’s premises or in a cloud platform of their choice.
• Public Cloud deployments leverage Cloudmersive’s multi-tenant public cloud offering.
• PaaS deployments take advantage of Azure App Service or Azure Kubernetes Service offerings.
• Government Cloud deployments take place in a specified government cloud region, suiting the data governance requirements of government entities.

Conclusion

CDR is a technology that rebuilds files security rather than only scanning them for viruses and other threats. It complements virus scanning in an enterprise security workflow rather than completely replacing it. In doing so, it bolsters enterprise protection against unknown threats, embedded threats, and zero-day threats.

To learn more about CDR integration for your enterprise environment, reach out to a Cloudmersive expert today.