[Rule Tuning] Windows High Severity - 5

[w0rk3r]

Issues

Part of https://github.com/elastic/ia-trade-team/issues/678

Summary

Lowers the severity of a few rules, logic adjusts to exclude FPs.

[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

• ❌ User account exposed to Kerberoasting (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Ransomware Behavior - High count of Readme files by System (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Bypass UAC via Event Viewer (eql)
  • stack_validation_failed: no_alerts - 0 alerts
• ❌ Windows Service Installed via an Unusual Client (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Suspicious Access to LDAP Attributes (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Privilege Escalation via Windir Environment Variable (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential privilege escalation via CVE-2022-38028 (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[w0rk3r]

This one is very noisy, and I couldn't find a way to tune it down

[w0rk3r]

Noisy and not great at performance, and the threshold rule type doesn't expose any information for us to work in a tuning. Lowering the severity until we work in a ES|QL Conversion

#4653

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ User account exposed to Kerberoasting (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Ransomware Behavior - High count of Readme files by System (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Bypass UAC via Event Viewer (eql)
  • stack_validation_failed: no_alerts - 0 alerts
• ❌ Windows Service Installed via an Unusual Client (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Suspicious Access to LDAP Attributes (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Privilege Escalation via Windir Environment Variable (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential privilege escalation via CVE-2022-38028 (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ User account exposed to Kerberoasting (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Ransomware Behavior - High count of Readme files by System (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Bypass UAC via Event Viewer (eql)
  • stack_validation_failed: no_alerts - 0 alerts
• ❌ Windows Service Installed via an Unusual Client (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Suspicious Access to LDAP Attributes (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Privilege Escalation via Windir Environment Variable (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential privilege escalation via CVE-2022-38028 (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta