Web Shell Classifier Training Using ML Feature Analysis

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Solution Overview

Problem

Existing techniques for detecting web shell applications are vulnerable to shifts in attacker behavior and require the file to be running to determine if it is malicious, often resulting in false positives and inadequate security against unauthorized access.

Innovation Solution

A method and system that utilize machine learning to classify files as web shell or non-web shell applications by extracting and analyzing static and dynamic features, such as index of coincidence, entropy rate, system function calls, and behavior in a controlled environment, using classifiers like gradient boosting and Extra Trees to provide probabilistic assessments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional signature-based detection methods are used, then detection simplicity is maintained, but detection accuracy deteriorates due to vulnerability to attacker behavior shifts

Engineering Contradiction:
Improvedetection accuracyVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent transforms the detection approach by changing from static signature parameters to dynamic behavioral parameters. Instead of relying on fixed file signatures, the system extracts multiple features (entropy rate, index of coincidence, function call patterns, nesting levels) and uses machine learning classifiers to detect web shells based on their behavioral characteristics, thereby improving detection accuracy against evolving threats.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical signature-matching system with a machine learning-based classification system. Gradient boosting and Extra Trees classifiers are trained on extracted features to automatically identify web shells, substituting the rigid mechanical comparison process with an adaptive intelligent system that can generalize to unknown threats.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If file execution is required for detection, then detection completeness improves, but system security deteriorates due to potential damage from executing malicious files

Engineering Contradiction:
Improvedetection completenessVSAvoidsystem damage risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent performs preliminary analysis by extracting static features (entropy rate, index of coincidence, function call patterns) from files before execution. This preliminary action allows the system to identify suspicious characteristics and classify potential web shells without actually executing the files, thus maintaining detection completeness while eliminating the security risk of running malicious code.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces a controlled analysis environment that acts as an intermediary between the file and the system. By analyzing files in this isolated intermediate state and using machine learning classifiers to evaluate extracted features, the system can safely determine maliciousness without direct execution on the target system.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If manually defined rules are used for detection, then ease of implementation is maintained, but adaptability deteriorates due to inability to respond to new attack patterns

Engineering Contradiction:
Improveresponse to new attacksVSAvoiddetection methodology complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces dynamics into the detection system by using machine learning classifiers that can adapt to new attack patterns. The gradient boosting and Extra Trees models are trained on extracted features and can generalize to previously unseen web shell variants, providing dynamic adaptability compared to static manual rules while maintaining a structured analytical framework.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS11354412B1Web shell classifier training
Publication Date: 2022.06.07 RAPID7 INC
  • US11354412B1 patent drawing
  • US11354412B1 patent drawing
  • US11354412B1 patent drawing

AI summary

Methods and systems for identifying malicious applications and, more particularly, to identifying web shell applications. Embodiments described herein rely on machine learning tools to analyze static and dynamic features of a suspected file to determine whether the file is a web shell application.