[Rule Tuning] AWS STS GetCallerIdentity API Called for the First Time

[imays11]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/616

Summary - What I changed

Rule is executing as expected with no troubling alerts in telemetry. For tuning I've:

• reduced the execution window
• removed MD from description and FP as it's not supported in Kibana UI
• edited some of the language of IG to speak about the exclusion of AssumedRoles and suggest user.id for exclusions over user.name as it a unique value across AWS accounts under the same Org.
• edited the highlighted fields for consistency across AWS rules
• update broken reference link

How To Test

You can use the following script to 1. create a new user 2. create a new role and 3. call the GetCallerIdentity API using both identities. To manually test you can follow the same steps. You don't need any special permissions to make this call.

Below is a screenshot of the expected alert after testing

[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.