Malware Detection via Metadata Statistical Scoring

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Solution Overview

Problem

Existing methods for identifying malware in electronic documents rely on pattern matching, which often results in false positives and false negatives due to focusing solely on data, missing embedded malware in metadata.

Innovation Solution

A statistical approach that analyzes metadata structures in electronic documents using pre-established rules to generate a numerical score, comparing it to a model threshold value to determine the likelihood of embedded malware, minimizing false positives and negatives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pattern matching is used to search for predefined byte sequences in document data, then documents with obvious malicious content can be identified, but malware embedded in metadata is missed and false positives occur

Engineering Contradiction:
Improvemalware detection accuracyVSAvoidfalse positive rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent segments the document analysis into two distinct parts: analyzing the visible data content using pattern matching, and analyzing the hidden metadata separately using statistical modeling. This segmentation allows each method to focus on its strengths without interfering with the other, thereby improving overall detection accuracy while reducing false positives from metadata anomalies

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces statistical modeling as an intermediary layer between the raw metadata and the detection decision. Instead of directly applying pattern matching to metadata, the system uses statistical models to interpret metadata patterns, which acts as a mediator that reduces false positives while maintaining detection of actual malware

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If pattern matching focuses only on document data, then processing is simple and fast, but malware hidden in metadata is completely missed

Engineering Contradiction:
Improvedetection speedVSAvoidmalware detection completeness
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent divides the detection system into two parallel segments: one processing data content for speed, and another processing metadata for completeness. Both segments operate independently and contribute to the final detection decision, ensuring neither speed nor completeness is compromised

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges the results from data-based pattern matching and metadata-based statistical modeling into a unified detection decision. This combination ensures that malware detected by either method will be identified, achieving both speed and completeness in malware detection

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If metadata is analyzed using statistical modeling, then malware embedded in metadata is detected, but the system complexity increases

Engineering Contradiction:
Improvemetadata malware detectionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses statistical models as intermediaries that automatically process metadata without requiring complex manual analysis rules. These models serve as ready-made analytical tools that reduce system complexity while maintaining high detection precision for metadata-based malware

Inventive Principle:
Principle #24Intermediary (Mediator)

4Extent of automation

If pre-established rules are applied to metadata structures, then automated scoring is achieved, but the initial model development requires significant effort

Engineering Contradiction:
Improveautomated document scoringVSAvoidmodel development effort
Core Design Contradiction:
Extent of automationVSEase of manufacture

Solution Approach 1:

The patent performs preliminary action by pre-establishing statistical models and rules during an offline phase using training data. This preliminary work automates the detection process for future documents, requiring significant effort only once during model development rather than for each individual document analysis

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS9177142B2Identification of electronic documents that are likely to contain embedded malware
Publication Date: 2015.11.03 TRUSTWAVE HOLDINGS INC
  • US9177142B2 patent drawing
  • US9177142B2 patent drawing
  • US9177142B2 patent drawing

AI summary

The present invention provides a method for determining the likelihood that an electronic document contains embedded malware. After parsing or sequencing an electronic document, the metadata structures that make up the document are analyzed. A number of pre-established rules are then applied with respect to certain metadata structures that are indicative of embedded malware. The application of these rules results in the generation of a score for the electronic document being tested for embedded malware. The score is then compared to a threshold value, where the threshold value was previously generated based on a statistical model relating to electronic documents having the same format as the document being tested. The result of the comparison can then be used to determine whether the document being tested is or is not likely to contain embedded malware.