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[Rule Tuning] Linux DR Tuning - 2 #5481

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@Aegrah Aegrah commented Dec 17, 2025

Summary

Misc. Linux DR Tunings

@Aegrah Aegrah self-assigned this Dec 17, 2025
@Aegrah Aegrah added OS: Linux Rule: Tuning tweaking or tuning an existing rule Team: TRADE labels Dec 17, 2025
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github-actions bot commented Dec 17, 2025

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 Dec 17, 2025 •
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⛔️ Test failed

Results
  • ❌ Potential Protocol Tunneling via Chisel Client (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ ProxyChains Activity (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ IPv4/IPv6 Forwarding Activity (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Suspicious Utility Launched via ProxyChains (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Linux Tunneling and/or Port Forwarding (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Protocol Tunneling via EarthWorm (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Deprecated - Potential Protocol Tunneling via Chisel Server (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Linux Telegram API Request (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta
  • ❌ Potential Linux Tunneling and/or Port Forwarding via SSH Option (eql)
    • coverage_issue: no_rta
    • stack_validation_failed: no_rta

Samirbous
Samirbous approved these changes Dec 17, 2025
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rules/linux/command_and_control_linux_proxychains_activity.toml
query = '''
process where host.os.type == "linux" and event.type == "start" and event.action in ("exec", "exec_event", "start", "ProcessRollup2", "executed", "process_started")
and process.name == "proxychains"
process where host.os.type == "linux" and event.type == "start" and
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@Samirbous Samirbous Dec 17, 2025

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is this just a format change ?

eric-forte-elastic
eric-forte-elastic reviewed Dec 18, 2025
View reviewed changes
rules/linux/command_and_control_ip_forwarding_activity.toml
process.parent.name like~ ("privsep-helper", "platform-python*", "init.ipv6-global", "wsl-bootstrap") or
?process.parent.executable == "/usr/sbin/sshd" or
?process.parent.args in (
"/usr/lib/pritunl/usr/bin/pritunl", "/usr/bin/dockerd-rootless.sh", "/etc/rc.d/init.d/network", "/etc/rc0.d/K90network"
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@eric-forte-elastic eric-forte-elastic Dec 18, 2025 •
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For "/usr/bin/dockerd-rootless.sh", from the docker docs (from Docker, and from VMware) it looks like this can also be invoked at setup not just in the ExecStart in the Docker service definition.

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eric-forte-elastic commented Dec 18, 2025

Looks good, minor comment, but not a blocker.

Happy to approve when https://github.com/elastic/detection-rules/pull/5481/changes#r2626499614 is resolved 👍

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@eric-forte-elastic eric-forte-elastic eric-forte-elastic left review comments

@Samirbous Samirbous Samirbous approved these changes

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backport: auto Domain: Endpoint OS: Linux Rule: Tuning tweaking or tuning an existing rule Team: TRADE

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