[New Rule] Potential ICMP Tunneling Activity to the Internet

[eric-forte-elastic]

Pull Request

Issue link(s):

Summary - What I changed

Adds a new new_terms network detection rule that identifies sustained ICMP Echo traffic from an internal host to an external destination with larger-than-typical transaction sizes. ICMP tunneling tools and covert channels can embed command-and-control or exfiltrated data in echo request and reply payloads, which may stand out from normal fixed-size ping behavior.

How To Test

RTA and shared data in stack.

Checklist

• Added a label for the type of pr: bug, enhancement, schema, maintenance, Rule: New, Rule: Deprecation, Rule: Tuning, Hunt: New, or Hunt: Tuning so guidelines can be generated
• Added the meta:rapid-merge label if planning to merge within 24 hours
• Secret and sensitive material has been managed correctly
• Automated testing was updated or added to match the most common scenarios
• Documentation and comments were added for features that require explanation

Contributor checklist

• Have you signed the contributor license agreement?
• Have you followed the contributor guidelines?

[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 ICMP Tunneling Activity to the Internet (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[Copilot]

Pull request overview

Adds a new network new_terms detection rule to identify potential ICMP tunneling/covert-channel activity by flagging unusually large ICMP Echo transactions from internal sources to external destinations.

Changes:

• Introduces a new new_terms rule targeting large ICMP Echo request traffic to the internet.
• Adds an investigation guide, setup requirements, and MITRE ATT&CK mappings for ICMP tunneling context.

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ Potential ICMP Tunneling Activity to the Internet (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta

[bryans3c]

LGTM!

[Aegrah]

Nice. Did you test ICMP tunneling tools such as e.g. Hans? https://github.com/albertzak/hanstunnel

[eric-forte-elastic]

Nice. Did you test ICMP tunneling tools such as e.g. Hans? https://github.com/albertzak/hanstunnel

Yes, not with Hans prior to this, but adding a test info for Hans specifically here.

This rule will not detect the creation or initial setup of the ICMP tunnel as this can be done with small echo packets.

E.g. Me setting up some tunnels on a local machine (network bytes usually around < 100 )

But will will detect when the tunnels are used (they will generally go above the 256 byte threshold).
E.g. two other machines setup with the tunnel with one using scp to move a file along the tunnel (slight IP addr filter modification given both VMs are internal)

[tradebot-elastic]

⛔️ Test failed

Results

• ❌ Potential ICMP Tunneling Activity to the Internet (kuery)
  • coverage_issue: no_rta
  • stack_validation_failed: no_rta