[New Rules] Linux ER Rule Migrations - Part 1

[Aegrah]

Summary

Migrating miscellaneous endpoint rules over to detection rules.

[github-actions]

Rule: New - Guidelines

These guidelines serve as a reminder set of considerations when proposing a new rule.

Documentation and Context

• Detailed description of the rule.
• List any new fields required in ECS/data sources.
• Link related issues or PRs.
• Include references.

Rule Metadata Checks

• creation_date matches the date of creation PR initially 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, considering performance for diverse environments. Non ecs fields should be added to non-ecs-schema.json if not available in an integration.
• min_stack_comments and min_stack_version should be included if the rule is only compatible starting from a specific stack version.
• index pattern should be neither too specific nor too vague, ensuring it accurately matches the relevant data stream (e.g., use logs-endpoint.process-* for process data).
• integration should align with the index. If the integration is newly introduced, ensure the manifest, schemas, and new_rule.yaml template are updated.
• setup should include the necessary steps to configure the integration.
• note should include any additional information (e.g. Triage and analysis investigation guides, timeline templates).
• tags should be relevant to the threat and align/added to the EXPECTED_RULE_TAGS in the definitions.py file.
• threat, techniques, and subtechniques should map to ATT&CK always if possible.

New BBR Rules

• building_block_type should be included if the rule is a building block and the rule should be located in the rules_building_block folder.
• bypass_bbr_timing should be included if adding custom lookback timing to the rule.

Testing and Validation

• Provide evidence of testing and detecting the expected threat.
• Check for existence of coverage to prevent duplication.

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ xdg-open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ xdg-open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[Copilot]

Pull request overview

This PR migrates a first batch of Linux Endpoint Response (ER) detections into the detection-rules repository as new Linux rules.

Changes:

• Added a Linux EQL rule for xdg-open execution.
• Added a Linux EQL sequence rule for interpreter-driven downloads piped into an interpreter.
• Added Linux EQL rules for Elastic Endpoint shell execution and suspicious DNS TLD lookups.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
rules/linux/execution_suspicious_xdg_open_command_execution.toml	New EQL process-start rule for xdg-open execution on Linux across multiple endpoint data sources.
rules/linux/execution_payload_downloaded_by_interpreter_and_piped_to_interpreter.toml	New EQL sequence correlating outbound network activity from interpreters followed by interpreter execution consistent with piped payload execution.
rules/linux/command_and_control_elastic_endpoint_shell_execution.toml	New EQL rule to detect shell execution attributed to Elastic Endpoint response actions.
rules/linux/command_and_control_dns_query_to_sus_top_level_domain.toml	New EQL rule to detect DNS queries to a list of suspicious/abused TLDs (min stack 9.3.0).

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ XDG-Open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ XDG-Open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[bryans3c]

LGTM

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ XDG-Open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ XDG-Open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ DNS Request to Suspicious Top Level Domain (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Payload Downloaded by Interpreter and Piped to Interpreter (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ XDG-Open Command Execution (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Shell Execution via Elastic Endpoint (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta