# How to Clean Files by Rebuilding Them Instead of Scanning Them

> A security method that stops malware by rebuilding files from scratch based on strict format rules, rather than looking for known viruses.

- **Patent:** US 9516045
- **Original title:** Resisting the spread of unwanted code and data
- **Owner:** Glasswall IP Ltd
- **Granted:** 2016
- **Status:** Active
- **Times cited:** 7
- **Field:** software, ai_ml, telecommunications

## What it does

This patent describes a file sanitization process that ignores the traditional 'detect and block' approach used by antivirus software. Instead of scanning for known malicious signatures, the system parses an incoming file to see if it matches a strict set of rules for its specific file type (like a PDF or Word doc). If the system finds data that doesn't fit the rules, it checks if that data is authorized; if so, it effectively 'rebuilds' the file from the ground up using only clean, verified data. This ensures the final output is a structurally perfect version of the original, leaving behind any hidden malicious code that might have been embedded in the non-conforming parts.

## What it does NOT cover

- Does not cover traditional antivirus methods that rely on signature-based scanning of files.
- Does not cover systems that simply delete non-conforming data without attempting to regenerate a valid file.
- Does not cover methods that do not perform a structural parse of the file's internal data format.

## The clever bit

The system treats the file as a set of rules rather than a static object, rebuilding it to be structurally compliant. By ignoring the 'content' and focusing on the 'format,' it makes it impossible for hidden malicious code to survive the reconstruction process.

## Real-world examples

1. Glasswall CDR technology
2. Email attachment sanitization gateways
3. Secure document upload portals

## Why it matters

This technology represents a shift toward 'Content Disarm and Reconstruction' (CDR). By focusing on the structure of a file rather than its reputation or signature, it can neutralize 'zero-day' threats—new viruses that antivirus software hasn't seen before. It is a critical component for high-security environments where the risk of an unknown file containing a hidden exploit is too high to ignore.

## Frequently asked questions

### What does How to Clean Files by Rebuilding Them Instead of Scanning Them cover?

A security method that stops malware by rebuilding files from scratch based on strict format rules, rather than looking for known viruses.

### Who owns patent US 9516045?

Glasswall IP Ltd owns this patent, granted in 2016.

### When does this patent expire?

This patent is expected to expire on December 6, 2036, when the invention enters the public domain.

### What is patent US 9516045 cited by?

This patent has been cited by 7 later patents that build on its ideas.

### What problem does this patent solve?

This technology represents a shift toward 'Content Disarm and Reconstruction' (CDR). By focusing on the structure of a file rather than its reputation or signature, it can neutralize 'zero-day' threats—new viruses that antivirus software hasn't seen before. It is a critical component for high-security environments where the risk of an unknown file containing a hidden exploit is too high to ignore.

### What does this patent NOT cover?

Does not cover traditional antivirus methods that rely on signature-based scanning of files.

**Full plain-English explainer:** https://patentbrief.org/patent/us/9516045/azure-active-directory

**Original patent:** https://patents.google.com/patent/US9516045

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._