[New Rule] TeamFiltration User-Agents Detected

[terrancedejesus]

Pull Request

Issue link(s):

• [New Rule] Potential TeamFiltration Tool Detected #4862

Summary - What I changed

Adds detection for TeamFiltration tool via hardcoded user agent. Checks for usage across M365 and Entra ID via Sign-In Logs.

How To Test

• Query can be used in TRADE stack to see recent tool usage.

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.

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• Detailed description of the rule.
• List any new fields required in ECS/data sources.
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Testing and Validation

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[w0rk3r]

@terrancedejesus I think that with no ()s this query is effective like this:

Condition 1:
event.dataset:(azure.signinlogs or o365.audit) and user_agent.name:Electron and user_agent.os.name:Windows and user_agent.version:8.5.1

Condition 2:
user_agent.original:"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Teams/1.3.00.30866 Chrome/80.0.3987.165 Electron/8.5.1 Safari/537.36"

Which is probably not prone to FPs, but it can still match unintended events

Example:

[terrancedejesus]

@w0rk3r - Thanks for the insight. I originally changed it due to KQL having issues with the "optimization" of it.

[terrancedejesus]

Adjusted the query to include a nested object instead to avoid any unintended events and fix query optimization.