[Rule Tuning] Lookback Times for Okta Multiple Session and AWS KMS Retrieval Rules

[terrancedejesus]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/272

Summary - What I changed

Adjusted the from and interval times for rules per @approksiu.

How To Test

Queries were adjusted for format, but no logic changes.

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?

[protectionsmachine]

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.

[Mikaayenson]

@terrancedejesus With some simple logic, there are a few identified:

Details

from detection_rules.rule_loader import RuleCollection
from detection_rules.utils import convert_time_span
rules = RuleCollection.default()


def convert_relative_delta(lookback: str) -> int:
    now = len("now")
    min_length = now + len('+5m')

    if lookback.startswith("now") and len(lookback) >= min_length:
        lookback = lookback[len("now"):]
        sign = lookback[0]  # + or -
        span = lookback[1:]
        amount = convert_time_span(span)
        return amount * (-1 if sign == "-" else 1)
    else:
        return convert_time_span(lookback)


for rule in rules.rules:
    to = convert_relative_delta(rule.contents.data.to) if rule.contents.data.to else 0
    from_ = convert_relative_delta(rule.contents.data.from_ or "now-6m")
    interval = convert_time_span(rule.contents.data.interval or "5m")
    if to - from_ <= interval:
        print(f"{rule.name} - {rule.id}")

My First Rule - a198fbbd-9413-45ec-a269-47ae4ccf59ce
Rapid Secret Retrieval Attempts from AWS SecretsManager - 185c782e-f86a-11ee-9d9f-f661ea17fbce
Multiple Okta Sessions Detected for a Single User - 621e92b6-7e54-11ee-bdc0-f661ea17fbcd
Query Registry using Built-in Tools - ded09d02-0137-4ccc-8005-c45e617e8d4c

Can you go ahead and fix the others?

FWIW, we could probably turn the code into a unit test. Starting in 8.18, when rules customization is released, the issue where this surfaces should be fixed by elastic/kibana#204317 .

[terrancedejesus]

@approksiu @Mikaayenson - If we want this different just let me know.