Detection Engineering Coverage Evaluation

SecOps Detection Coverage Skill

This skill guides the agent through an end-to-end detection engineering lifecycle using Google SecOps MCP tools. It handles multiple Threat Detection Opportunities (TDOs) and ensures exhaustive coverage evaluation for all generated synthetic events.

Workflow Execution Checklist

Copy this checklist and track progress for each iteration:

• Step 1: Extract raw text content from a source (for example, blog URL).
• Step 2: Generate Threat Detection Opportunities (TDOs).
• Step 3: Loop through ALL TDOs to generate synthetic events.
• Step 4: Loop through ALL UDM events to evaluate rule coverage.
• Step 5: For identified rules, check enablement and alerting status.
• Step 6: Generate new rules for identified gaps.
• Step 7: Provide a structured summary of findings and gaps.
• Step 8: Ask the user to approve adding newly generated rules to their SecOps environment and create them.

Detailed Steps

1. Extract Threat Intelligence

• Use the following prompt to extract all text content from a URL: - "Fetch the blog text from {url}. You need to extract and output the entire text content of the page, exactly as it appears in the HTML, without any summarization, modification, or omission."

• Summary of Step: Report only that the text was successfully extracted from the provided URL. Do not output the full raw text.

• Next Step: The extracted text will be used to generate Threat Detection Opportunities (TDOs).

2. Generate TDOs

• Call generate_threat_detection_opportunity with the extracted full blog threat raw text. You must not summarize. This tool returns one or more TDOs.

• Summary of Step: Report the number of TDOs generated and provide a brief, high-level summary for each TDO (for example, the key threat or attacker technique identified). Do not output the full TDO JSON.

• Next Step: The process will now loop through each generated TDO to create synthetic events.

3. Generate Synthetic Events (For ALL TDOs)

For every TDO:

• Call generate_synthetic_events using the TDO.

• Summary of Step: Report the total number of synthetic UDM events generated for this TDO. Briefly describe the types of attacker behaviors simulated (for example, "Generated events simulating initial access and privilege escalation"). Don't output the full response.

• Next Step: The generated UDM events will be used to evaluate rule coverage.

4. Evaluate Rule Coverage (For ALL UDM Events)

For every UDM event generated for a TDO:

• Call evaluate_rule_coverage by providing the UDM event in valid JSON format. Provide only the UDM event as a single, valid JSON object. You MUST Provide each UDM event as a standard stringified JSON object within the udmsJson list. Do not apply an additional layer of escaping to the JSON string. Provide a standard JSON stringification with no extra backslashes.

• Summary of Step: Report which rule_ids matched for this event, if any. If no rules matched, clearly state "No rules matched." Provide counts of events evaluated. Don't output the full coverage evaluation JSON.

• Next Step: The identified matched rules will be audited for their enablement and alerting status.

5. Audit Rule Status

For every distinct rule_id identified:

• Call get_rule to check the rule configuration with CONFIG_ONLY view.

• Summary of Step: For each rule_id, state its enablement status (for example, "Enabled", "Disabled") and alerting status (for example, "Alerting Enabled", "Alerting Disabled").

• Next Step: Review coverage gaps and potentially generate new rules.

6. Gap Mitigation

If gaps are found:

• Call generate_rules for the relevant TDOs.

• Summary of Step: For each gap, describe what coverage was missing and confirm if a new rule was generated. Provide a brief summary of what the newly generated rule aims to detect.

• Next Step: Provide a final structured summary of all findings and gaps.

7. Provide Summary

• Format and present a final structured summary of all findings and gaps. Refer to the Output Format section below for the required schema.

• Summary of Step: Present the structured summary of TDOs, coverage, missing coverage, and errors.

• Next Step: Ask the user if they would like to create the newly generated rules in their SecOps environment.

8. Rule Creation

• If new rules were generated in Step 6, present them to the user and ask if they would like to create these rules in their SecOps environment. Allow the user to approve or reject each rule. For each approved rule, use the user's configured SecOps MCP server and the SecOps tool create_rule to add the rule to their SecOps environment. Pass the YARA-L rule text string via the rule parameter of the create_rule tool.

• Summary of Step: Report which rules were approved and successfully created in the SecOps environment.

• Next Step: The detection engineering coverage evaluation workflow is complete.

Output Format

Provide a summary for each TDO processed:

TDO: {tdo summary}

Coverage Eval: [{rule_id, enablement status, alerting status}, ...]

Missing Coverage: [{summary, generated rule}] // Only if gaps exist

Errors: [{if any any errors encountered, specify the tool}]

Tool Reference

• generate_threat_detection_opportunity: Initial tool for threat analysis.
• generate_synthetic_events: Generates logs simulating the TDO.
• evaluate_rule_coverage: Checks if existing rules detect the synthetic UDMs.
• get_rule: Use to check alerting_enabled and enabled status of SIEM rules.
• generate_rules: Codifies detection logic for gaps.
• create_rule: Deploys the rule in the SecOps environment.

Source: google/skills → skills/cloud/detection-engineering-coverage-evaluation/SKILL.md