[Rule Tuning] Windows 3rd Party EDR Compatibility - Part 8

[w0rk3r]

Issue

Related (but not limited) to https://github.com/elastic/ia-trade-team/issues/498

Summary

This PR is part of a series that adds compatibility for additional data sources, including CrowdStrike, SentinelOne, Microsoft Defender for Endpoint, Endgame, and Sysmon.

To review this PR, you can use the EDR Field Compatibility Matrix, which details field compatibility for each event.category across EDR data sources.

Some changes go beyond metadata and include logic updates to optimize, simplify, or account for differences between data sources (For example, CrowdStrike uses NT Object paths for Windows paths instead of drive letters.). Please review these cases with extra attention, and don’t hesitate to ask questions.

[github-actions]

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.

[tradebot-elastic]

⛔️ Test failed

Results

• ✅ Potential Evasion via Filter Manager (eql)
• ❌ WDAC Policy File by an Unusual Process (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Process Network Connection (eql)
• ❌ Host Files System Changes via Windows Subsystem for Linux (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Executable File Creation by a System Critical Process (eql)

[Samirbous]

this rule looks like a dup of https://github.com/elastic/detection-rules/blob/fbfc696a86d3ec826fbd13fb8957d294f155dc17/rules/windows/defense_evasion_network_connection_from_windows_binary.toml and we need to fix rules scope duplicate unless its justified by having multi-versions to support different datasources.

[w0rk3r]

It seems that both existed since the beginning of the repo, but yeah, there is definitely a lot of overlap. I'll take a look at this outside this PR and probably deprecate this one. +1 to my todo

[tradebot-elastic]

⛔️ Test failed

Results

• ✅ Potential Evasion via Filter Manager (eql)
• ❌ WDAC Policy File by an Unusual Process (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Process Network Connection (eql)
• ❌ Host Files System Changes via Windows Subsystem for Linux (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Executable File Creation by a System Critical Process (eql)

[tradebot-elastic]

⛔️ Test failed

Results

• ✅ Potential Evasion via Filter Manager (eql)
• ❌ WDAC Policy File by an Unusual Process (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Process Network Connection (eql)
• ❌ Host Files System Changes via Windows Subsystem for Linux (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Executable File Creation by a System Critical Process (eql)

[terrancedejesus]

Maybe ignore trusted install worker here?

[w0rk3r]

I'll review these rules for tunings as part of https://github.com/elastic/ia-trade-team/issues/619

[tradebot-elastic]

⛔️ Test failed

Results

• ✅ Potential Evasion via Filter Manager (eql)
• ❌ WDAC Policy File by an Unusual Process (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Process Network Connection (eql)
• ❌ Host Files System Changes via Windows Subsystem for Linux (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ✅ Unusual Executable File Creation by a System Critical Process (eql)