Add O365 rule: Inbox Forward Rule with Email Exfiltration#2221
Merged
Kbayero merged 1 commit intoJun 15, 2026
Merged
Conversation
❌ Go dependencies check failedThere are outdated Go dependencies, or modules that could not be inspected. Script output |
|
![utmstackprapprover[bot]](https://avatars.githubusercontent.com/u/144401876?s=60&v=4){kind=small}
Kbayero
approved these changes
Jun 15, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Changes
Adds a new O365 correlation rule o365-inbox-forward-rule-exfiltration.yml that detects the creation or modification of inbox forwarding rules followed by a burst of SendAs activity from the same user within 1 hour.
Reasoning
A forwarding/inbox rule on its own is noisy — many users legitimately create them. The high-fidelity signal is the combination: an inbox rule created or modified, immediately followed by a burst of activity from the same identity. That pattern is a textbook business-email-compromise / account-takeover exfiltration playbook: the attacker pivots inbound mail and then actively impersonates the user. The 1-hour window with keeps false positives down while preserving recall on real incidents.
Issue Reference
N/A