URL Verdict Recrawling Policy for Stable Malicious Classification

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Solution Overview

Problem

Cybersecurity systems face challenges in maintaining stable and accurate verdicts for URLs due to the volatility of web page behavior, leading to resource wastage from frequent recrawling or inaccuracies from stale verdicts, especially when flipping malicious to benign verdicts.

Innovation Solution

Implementing a recrawling policy that intelligently recrawls URLs with progressively less frequency over observation windows, using a URL classification model and a flipping model trained on ground truth verdicts to determine when to flip verdicts from malicious to benign and back, thereby reducing resource wastage and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequent recrawling is performed to maintain accurate verdicts, then verdict accuracy is improved, but resource consumption increases

Engineering Contradiction:
Improveverdict accuracyVSAvoidresource consumption
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The system implements periodic recrawling with observation windows of specific durations (e.g., 30 days for benign URLs, 90 days for malicious URLs). Recrawling occurs at predetermined intervals within these windows rather than continuously, reducing resource consumption while maintaining verdict accuracy through systematic periodic verification.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The recrawling frequency is dynamically adjusted based on the verdict type and observation window progress. The system transitions from frequent recrawling at the start of an observation window to less frequent recrawling as the window progresses, optimizing resource allocation while maintaining adequate verification coverage.

Inventive Principle:
Principle #15Dynamics

2Loss of energy

If recrawling frequency is reduced to save resources, then resource consumption decreases, but verdict stability deteriorates

Engineering Contradiction:
Improveresource consumptionVSAvoidverdict stability
Core Design Contradiction:
Loss of energyVSStability of the object's composition

Solution Approach 1:

The system uses feedback from previous recrawling results to determine subsequent recrawling frequency and timing. Verdict information from prior recrawls is fed back into the decision logic for scheduling future recrawls, allowing the system to maintain verdict stability by recrawling more frequently when verdicts are volatile and less frequently when verdicts are stable.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary recrawling at the beginning of observation windows to establish baseline verdicts before reducing recrawling frequency. This preliminary action ensures that verdict stability is maintained during the critical transition period when URLs may exhibit volatile behavior, while resources are conserved during later periods when verdicts are more stable.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If verdicts are flipped quickly in response to new information, then verdict accuracy is improved, but verdict volatility increases

Engineering Contradiction:
Improveverdict accuracyVSAvoidverdict volatility
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The system implements cushioning mechanisms before flipping verdicts by requiring multiple recrawls within observation windows to confirm verdict changes. This buffer prevents premature verdict flips based on single anomalous recrawling results, reducing verdict volatility while maintaining the ability to flip verdicts when there is consistent evidence of malicious or benign behavior.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The system uses its own recrawling data and verdict history to automatically determine when verdict flips are warranted, without external intervention. The self-service mechanism incorporates built-in verification through multiple recrawls and observation windows, ensuring that verdict flips occur only when there is sufficient evidence, thereby reducing unnecessary volatility while maintaining accuracy.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS20250350614A1Maintaining stable uniform resource locator verdicts with intelligent recrawling
Publication Date: 2025.11.13 PALO ALTO NETWORKS INC
  • US20250350614A1 patent drawing
  • US20250350614A1 patent drawing
  • US20250350614A1 patent drawing

AI summary

A stable verdict recrawling policy maintains stable stored verdicts for uniform resource locators (URLs) with intelligent recrawling. Based on a malicious stored verdict for a URL, a web crawler initiates the recrawling policy. In a first observation window, a web crawler recrawls the URL at successively more infrequent times to obtain verdicts for the URL. If there are enough benign verdicts after the first observation window, a URL verdict flipping model receives recrawling data as input and outputs a flipping verdict indicating whether to flip the stored verdict from malicious to benign. If the stored verdict is flipped, in a second observation window the web crawler recrawls the URL at successively more infrequent times to obtain verdicts. If there is a malicious verdict in the second observation window, the stored verdict is again flipped from benign to malicious.