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[Rule Tuning] Windows High-Severity Rules Revamp - 2#5900

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w0rk3r wants to merge 5 commits intomainfrom
revamp_1
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[Rule Tuning] Windows High-Severity Rules Revamp - 2#5900
w0rk3r wants to merge 5 commits intomainfrom
revamp_1

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@w0rk3r w0rk3r commented Mar 30, 2026 •
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Issues

Part of https://github.com/elastic/ia-trade-team/issues/619
Part of https://github.com/elastic/ia-trade-team/issues/844
Part of https://github.com/elastic/ia-trade-team/issues/205
Part of https://github.com/elastic/ia-trade-team/issues/636

Summary

This PR fixes/improves our Windows rules by:

  • Improves our investigation guides to be question-driven and actionable, with clear pivots and specific information vs our old checklists
  • Tune the rules to exclude noisy patterns, fix the logic, or expand coverage.
  • Add setup guides to these rules
  • Add Highlighted fields
  • Fix/Improve metadata where needed
  • Improve the order of the fields, so the most relevant information (Name, description, query) are visible without scrolling down too much

Screenshots / Sample

Highlighted Fields:

image

Investigation Guides: Investigate Plugin

image

Clickling on them will launch a timeline with field values populated dynamically by event fields.

image image

@w0rk3r w0rk3r self-assigned this Mar 30, 2026
@w0rk3r w0rk3r added Rule: Tuning tweaking or tuning an existing rule OS: Windows windows related rules Domain: Endpoint backport: auto labels Mar 30, 2026
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github-actions bot commented Mar 30, 2026

Rule: Tuning - Guidelines

These guidelines serve as a reminder set of considerations when tuning an existing rule.

Documentation and Context

  • Detailed description of the suggested changes.
  • Provide example JSON data or screenshots.
  • Provide evidence of reducing benign events mistakenly identified as threats (False Positives).
  • Provide evidence of enhancing detection of true threats that were previously missed (False Negatives).
  • Provide evidence of optimizing resource consumption and execution time of detection rules (Performance).
  • Provide evidence of specific environment factors influencing customized rule tuning (Contextual Tuning).
  • Provide evidence of improvements made by modifying sensitivity by changing alert triggering thresholds (Threshold Adjustments).
  • Provide evidence of refining rules to better detect deviations from typical behavior (Behavioral Tuning).
  • Provide evidence of improvements of adjusting rules based on time-based patterns (Temporal Tuning).
  • Provide reasoning of adjusting priority or severity levels of alerts (Severity Tuning).
  • Provide evidence of improving quality integrity of our data used by detection rules (Data Quality).
  • Ensure the tuning includes necessary updates to the release documentation and versioning.

Rule Metadata Checks

  • updated_date matches the date of tuning PR merged.
  • min_stack_version should support the widest stack versions.
  • name and description should be descriptive and not include typos.
  • query should be inclusive, not overly exclusive. Review to ensure the original intent of the rule is maintained.

Testing and Validation

  • Validate that the tuned rule's performance is satisfactory and does not negatively impact the stack.
  • Ensure that the tuned rule has a low false positive rate.

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tradebot-elastic commented Mar 30, 2026 •
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⛔️ Test failed

Results
  • ❌ NetSupport Manager Execution from an Unusual Path (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Remote Desktop Tunneling Detected (eql)
    • stack_validation_failed: no_alerts - 0 alerts
  • ❌ Newly Observed ScreenConnect Host Server (esql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Outlook Home Page Registry Modification (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential REMCOS Trojan Execution (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta

Samirbous
Samirbous approved these changes Mar 30, 2026
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@Samirbous Samirbous left a comment

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In general its Ok but would be ideal if we can shorten those IG to the key point to make it easier for user to read/digest.

rules/windows/command_and_control_rdp_tunnel_plink.toml

This alert fires when a process starts with an explicit SSH port-forwarding flag ("-L" or "-R") targeting RDP port 3389. Treat it as evidence of attempted tunnel setup, not proof that the tunnel connected or that RDP traffic traversed it. Prioritize the forwarding direction and exposed target, whether the SSH client and launch chain fit expected administration, and whether nearby trust-seeding, network, or persistence artifacts show the tunnel being staged for reuse.

#### Possible investigation steps
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can we shorten a bit those IG steps to focus on main/key steps

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@w0rk3r w0rk3r Apr 1, 2026

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Shortened them in about 22% (avg), I think this is now in good balance

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tradebot-elastic commented Mar 30, 2026 •
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⛔️ Test failed

Results
  • ❌ NetSupport Manager Execution from an Unusual Path (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Remote Desktop Tunneling Detected (eql)
    • stack_validation_failed: no_alerts - 0 alerts
  • ❌ Newly Observed ScreenConnect Host Server (esql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Outlook Home Page Registry Modification (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential REMCOS Trojan Execution (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta

@w0rk3r w0rk3r marked this pull request as draft March 31, 2026 18:30
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tradebot-elastic commented Apr 1, 2026 •
edited
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⛔️ Test failed

Results
  • ❌ NetSupport Manager Execution from an Unusual Path (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Remote Desktop Tunneling Detected (eql)
    • stack_validation_failed: no_alerts - 0 alerts
  • ❌ Newly Observed ScreenConnect Host Server (esql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Outlook Home Page Registry Modification (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential REMCOS Trojan Execution (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta

@w0rk3r w0rk3r marked this pull request as ready for review April 1, 2026 01:54
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tradebot-elastic commented Apr 1, 2026 •
edited
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⛔️ Test failed

Results
  • ❌ NetSupport Manager Execution from an Unusual Path (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Remote Desktop Tunneling Detected (eql)
    • stack_validation_failed: no_alerts - 0 alerts
  • ❌ Newly Observed ScreenConnect Host Server (esql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Outlook Home Page Registry Modification (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential REMCOS Trojan Execution (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta

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Reviewers

@Samirbous Samirbous Samirbous approved these changes

@terrancedejesus terrancedejesus terrancedejesus approved these changes

@Mikaayenson Mikaayenson Awaiting requested review from Mikaayenson

@Aegrah Aegrah Awaiting requested review from Aegrah

@shashank-elastic shashank-elastic Awaiting requested review from shashank-elastic

@eric-forte-elastic eric-forte-elastic Awaiting requested review from eric-forte-elastic

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