[New Rules] Potential Relay Attack against a Computer Account

[w0rk3r]

Summary

Introduce 2 new rules to cover potential relay attacks by identifying coercion attempts followed by authentication events using a target server's computer account, originating from a different host. This may indicate that an attacker has captured and relayed the server's computer account hash to execute code on behalf of the compromised system.

Expands an existing detection to cover related activity, with reduced confidence.

Blocker

This PR is blocked by an potential EQL bug that prevents us from using winlog.computer_name in the sequence condition. Slack thread

[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

• ❌ Potential NTLM Relay Attack against a Computer Account (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Computer Account Relay Activity (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Kerberos Relay Attack against a Computer Account (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ Potential NTLM Relay Attack against a Computer Account (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Computer Account Relay Activity (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta
• ❌ Potential Kerberos Relay Attack against a Computer Account (eql)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta