diff --git a/detection-rules/impersonation_microsoft_teams.yml b/detection-rules/impersonation_microsoft_teams.yml index 2dfaee5e5c5..6e61e51d22f 100644 --- a/detection-rules/impersonation_microsoft_teams.yml +++ b/detection-rules/impersonation_microsoft_teams.yml @@ -9,19 +9,34 @@ source: | .file_type in $file_types_images or .file_type == "pdf" ) ) < 10 - and any(attachments, - (.file_type in $file_types_images or .file_type == "pdf") - and any(file.explode(.), - regex.icontains(.scan.ocr.raw, - "trying to reach you.*microsoft teams" - ) - ) + and ( + regex.icontains(body.current_thread.text, + 'trying to reach you.*microsoft teams', + 'new message in teams' + ) + or any(attachments, + (.file_type in $file_types_images or .file_type == "pdf") + and any(file.explode(.), + regex.icontains(.scan.ocr.raw, + "trying to reach you.*microsoft teams" + ) + ) + ) ) - and sender.email.domain.root_domain not in ( - "microsoft.com", - "microsoftsupport.com", - "office.com" + // not sent via legitimate Microsoft infra + and not strings.ends_with(headers.message_id, '@odspnotify>') + and not ( + sender.email.domain.root_domain in ( + "microsoft.com", + "microsoftsupport.com", + "office.com", + "mail.microsoft", + "service-now.com", + "atlassian.net" + ) + and coalesce(headers.auth_summary.dmarc.pass, false) ) + attack_types: - "Credential Phishing" tactics_and_techniques: