Differential Dependency Tracking for Intrusion Forensics

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Solution Overview

Problem

Conventional systems for backtracking attacks in enterprise computing systems face challenges due to the complexity of modern enterprise systems, leading to large and unmanageable backtracking graphs that include irrelevant dependencies, making it difficult to accurately detect and track attacks.

Innovation Solution

The method employs differential dependency tracking by generating audit logs, creating dependency graphs, determining relevancy scores, and pruning irrelevant events to condense backtracking graphs, thereby reducing computational demands and improving intrusion detection and recovery processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional backtracking systems include all dependencies in enterprise systems, then comprehensive attack tracking is achieved, but the backtracking graph size becomes unmanageably large and complex

Engineering Contradiction:
Improveattack tracking accuracyVSAvoidbacktracking graph complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes irrelevant dependencies from the backtracking graph by comparing audit logs against the dependency graph. Only dependencies that are actually relevant to the attack path are retained, while unnecessary nodes and edges are pruned away. This extraction process maintains attack tracking accuracy while dramatically reducing graph complexity and size.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the enterprise system dependencies into relevant and irrelevant portions based on audit log analysis. By dividing the complete dependency graph into attack-relevant subgraphs and irrelevant portions, the system can focus computational resources on analyzing only the necessary segments, reducing overall complexity while maintaining comprehensive attack tracking.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If conventional systems filter out certain attack-related events to simplify analysis, then graph size is reduced, but accuracy of attack detection deteriorates

Engineering Contradiction:
Improvebacktracking graph sizeVSAvoidattack detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent uses audit logs as feedback to dynamically determine which dependencies are relevant to the attack. By continuously comparing system events against the dependency graph and updating relevance assessments, the system accurately identifies attack-related dependencies without incorrectly filtering out important events. This feedback mechanism ensures both graph size reduction and detection accuracy are maintained.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the parameter of dependency relevance by dynamically assessing which dependencies are actually involved in the attack based on audit log analysis. Rather than using static filtering rules that may incorrectly exclude relevant events, the system adapts its relevance criteria based on observed system behavior, ensuring accurate attack detection while managing graph size.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If comprehensive monitoring of all hosts is performed, then complete attack visibility is achieved, but computational demands and processing time increase significantly

Engineering Contradiction:
Improveattack detection completenessVSAvoidprocessing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent extracts only the attack-relevant portion of the enterprise system by comparing audit logs against the dependency graph. Instead of processing all monitored host data, the system extracts and analyzes only those dependencies that are actually involved in the attack path. This extraction maintains complete attack visibility while dramatically improving processing efficiency by eliminating unnecessary computational overhead.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary analysis by building the dependency graph and comparing it against audit logs before conducting full backtracking analysis. This preliminary action identifies and pre-filters relevant dependencies, so that when actual attack analysis is needed, the system already has a streamlined set of relevant data to work with, significantly improving processing efficiency while maintaining detection completeness.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3205072B1Differential dependency tracking for attack forensics
Publication Date: 2021.03.31 NEC CORP
  • EP3205072B1 patent drawingFigure 1
  • EP3205072B1 patent drawingFigure 2A~2B
  • EP3205072B1 patent drawingFigure 3A~3B

AI summary

Methods and systems for intrusion attack recovery include monitoring (502) two or more hosts in a network to generate audit logs of system events. One or more dependency graphs (DGraphs) is generated (504) based on the audit logs. A relevancy score for each edge of the DGraphs is determined (510). Irrelevant events from the DGraphs are pruned (510) to generate a condensed backtracking graph. An origin is located by backtracking (512) from an attack detection point in the condensed backtracking graph.