diff --git a/rules/integrations/o365/defense_evasion_exchange_new_inbox_rule_delete_or_move.toml b/rules/integrations/o365/defense_evasion_exchange_new_inbox_rule_delete_or_move.toml index e38db88a5..146cb01f0 100644 --- a/rules/integrations/o365/defense_evasion_exchange_new_inbox_rule_delete_or_move.toml +++ b/rules/integrations/o365/defense_evasion_exchange_new_inbox_rule_delete_or_move.toml @@ -2,10 +2,10 @@ creation_date = "2025/05/22" integration = ["o365"] maturity = "production" -updated_date = "2025/12/10" +updated_date = "2026/01/29" [rule] -author = ["Elastic", "Jamie Lee"] +author = ["Elastic", "Jamie Lee", "Marco Pedrinazzi"] description = """ Identifies when a user creates a new inbox rule in Microsoft 365 that deletes or moves emails containing suspicious keywords. Adversaries who have compromised accounts often create inbox rules to hide alerts, security notifications, or @@ -84,8 +84,11 @@ type = "new_terms" query = ''' event.dataset: "o365.audit" and - event.action: "New-InboxRule" and event.outcome: "success" and - o365.audit.Parameters.SubjectContainsWords: ( + event.action: ("New-InboxRule" or "Set-InboxRule") and event.outcome: "success" and + ( + o365.audit.Parameters.BodyContainsWords: "\u0000" or + o365.audit.Parameters.WithinSizeRangeMinimum <= 1023 or + o365.audit.Parameters.SubjectContainsWords: ( *phish* or *hack* or *alert* or @@ -101,12 +104,14 @@ event.dataset: "o365.audit" and *protection* or *login* or *suspicious* + ) ) and ( o365.audit.Parameters.DeleteMessage: True or o365.audit.Parameters.MoveToFolder: ( *Deleted* or *Junk* or - *RSS* + *RSS* or + *Calendar* ) ) '''