Detection Coverage Calculator

Detection Coverage Calculator

Calculator Overview

The Detection Coverage Calculator automates the evaluation of detection coverage by analyzing what detection logic actually observes, looking deeper than just what it is mapped to.

The DCC evaluates detection content across two complementary dimensions: Detection Quality, measured through robustness and precision, and Implementation Coverage, which measures how much of the known behavioral implementation space for a mapped ATT&CK technique is detected. The result provides a more evidence-based view of coverage: what behavior is detected, how durable and precise the underlying detection signals are, and where meaningful gaps remain.

How It Works

The DCC brings together four components to connect ATT&CK techniques to observable behavior and detection logic.

Implementation Catalog

The Implementation Catalog describes behaviorally distinct ways of executing ATT&CK techniques. Built from ATT&CK procedure examples and Atomic Red Team tests, the catalog normalizes specific examples into reusable implementation paths and identifies the system interactions required to perform them. The DCC uses the catalog as the behavioral baseline against which Implementation Coverage is measured.

Sensor Mappings

Sensor-Field Mappings connect system activity to the telemetry available to observe it. The DCC extends previous sensor-mapping work with field-level information for supported telemetry sources, allowing it to evaluate the specific fields used by detection logic rather than treating the presence of an event or data source as sufficient evidence of detection.

This project produced a structured dataset of Windows Event Log reference fields indexed by Windows Event ID. The purpose of the dataset was to create a consistent set of XML fields found within common and advanced Windows Security auditing events, and to provide a foundation for later analytic work. The work was limited to documenting the published XML structure and normalizing to appropriate fields. The derived data set does not directly interpret the meaning of individual fields or create specific detection mappings. The example below demonstrates how a Windows Event Log entry is mapped.

Example Usage:

<System>
   <Provider Name="Microsoft-Windows-Security-Auditing"/>
   <EventID>4624</EventID>
   <Version>2</Version>
   ...
</System>

<EventData>
   <Data Name="SubjectUserSid"/>
   <Data Name="SubjectUserName"/>
   <Data Name="SubjectDomainName"/>
   <Data Name="TargetUserSid"/>
   <Data Name="TargetUserName"/>
   <Data Name="TargetDomainName"/>
   <Data Name="LogonType"/>
   <Data Name="IpAddress"/>
   <Data Name="IpPort"/>
</EventData>

System Fields

XML field

Reference field

Provider.Name

System.Provider.Name

EventID

System.EventID

Version

System.Version

TimeCreated.SystemTime

System.TimeCreated.SystemTime

Computer

System.Computer

Event Data Fields

XML field

Reference field

SubjectUserSid

EventData.SubjectUserSid

SubjectUserName

EventData.SubjectUserName

SubjectDomainName

EventData.SubjectDomainName

TargetUserSid

EventData.TargetUserSid

TargetUserName

EventData.TargetUserName

TargetDomainName

EventData.TargetDomainName

LogonType

EventData.LogonType

IpAddress

EventData.IpAddress

IpPort

EventData.IpPort

Analytic Ingestion

The Ingestion step in the pipeline automates rule processing for all of your detection logic. The script recursively steps through a rule directory and its subdirectories and pulls the values from each rule that the calculator needs to determine a coverage score.

There is no need to clean up the directory. It steps through level by level and only loads in YAML files. The process then uses a combination of regular expressions and context clues to extract the information.

Extracted Fields:

Field Extracted

Description

rule_title

The title of the SIGMA rule

rule_logsource_product

The product that the rule was created to defend

rule_logsource_category

The type of log that the rule is from

rule_tags

Any tags that the rule is with. Mainly ATT&CK Techniques and Tactics

detection_fields

The fields the rule uses to detect the activity

detection_filters

Any filters the rule may use

detection_condition

What causes the rule to trigger a positive detection

Example

Take the following rule, for example.

Sigma Rule: WMI Persistence - Security

It is a rule to detect WMI Persistance from the Windows Security logs.

The script, analyzes the rule, and creates the following JSON.

Sigma Rule: WMI Persistence - Security

With this formatted output, the next step in the pipeline can now take place.

Scoring Dictionary

The Scoring Dictionary provides standardized robustness and precision values for supported telemetry sources and fields. The DCC uses these values to automatically evaluate the Detection Quality of the signals used by an analytic.

Scoring Dictionary Excerpt

Using the Calculator

Supported Detection Formats

The current DCC supports Sigma specification-formatted YAML detection content and can process Sigma files stored locally or in a GitHub repository. The ingestion framework is designed to support additional detection formats as the project evolves.

Running an Assessment

Users provide detection content for analysis. The DCC parses each analytic, resolves its ATT&CK mapping and telemetry dependencies, evaluates its detection logic, and compares that evidence against the Implementation Catalog and Scoring Dictionary.

A valid ATT&CK mapping is required because the DCC evaluates the analytic against implementations of its stated technique; it does not infer missing technique mappings. Telemetry fields must likewise be recognizable within the supported Sensor Mappings for automated Detection Quality scoring.

Interpreting Results

DCC results should be used to identify opportunities for detection engineering—not simply to maximize a score.

Results can highlight:

  • behavioral implementations that lack detection coverage;

  • detections that depend on fragile or low-precision signals;

  • ATT&CK mappings that may not be supported by the detection logic;

  • telemetry limitations preventing stronger detection; and

  • areas where additional engineering investment could meaningfully improve coverage.

A low score does not necessarily mean an analytic is ineffective for its intended purpose. A narrowly targeted analytic may be valuable while providing limited evidence of broader technique coverage.

Generating Reports

The DCC produces detailed spreadsheet output containing analytic- and technique-level results and supports generation of an executive-oriented coverage report. These outputs provide both the underlying assessment data and a higher-level view of Detection Quality, Implementation Coverage, and identified gaps.

We have also developed a ChatGPT skill that takes the spreadsheet as an input to generate an executive-level report highlighting major findings and giving more of an overview of the results to assist in decision-making. Both are available in our STP Github repository!

Executive Coverage Report Snippet

GitHub / Download

View the Detection Coverage Calculator on GitHub

The project repository contains the DCC, supporting data, and documentation needed to run coverage assessments.