Name:O365 Email Access By Security Administrator id:c6998a30-fef4-4e89-97ac-3bb0123719b4 version:2 date:2024-09-30 author:Steven Dick status:production type:TTP Description:The following analytic identifies when a user with sufficient access to O365 Security & Compliance portal uses premium investigation features (Threat Explorer) to directly view email. Adversaries may exploit privileged access with this premium feature to enumerate or exfiltrate sensitive data. Data_source:
-O365 Universal Audit Log
search:`o365_management_activity` Workload=SecurityComplianceCenter Operation=AdminMailAccess | stats values(Workload) as category, values(MailboxId) as user, values(Operation) as signature, count, min(_time) as firstTime, max(_time) as lastTime by InternetMessageId, UserId | rename InternetMessageId as signature_id, UserId as src_user | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `o365_email_access_by_security_administrator_filter`
how_to_implement:You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. Threat Explorer is a premium feature with o365, logging may not be available with proper license. known_false_positives:Legitamate access by security administators for incident response measures. References: -https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/threat-explorer-investigate-delivered-malicious-email?view=o365-worldwide drilldown_searches: name:'View the detection results for - "$user$" and "$src_user$"' search:'%original_detection_search% | search user = "$user$" src_user = "$src_user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$" and "$src_user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$src_user$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Data Exfiltration' - 'Azure Active Directory Account Takeover' - 'Office 365 Account Takeover' asset_type:O365 Tenant confidence:50 impact:50 message:A security administrator $src_user$ accessed email messages for $user$ mitre_attack_id: - 'T1567' - 'T1114' - 'T1114.002' observable: name:'user' type:'User' - role: - 'Victim' name:'src_user' type:'User' - role: - 'Victim' name:'signature_id' type:'Other' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Workload' - 'Operation' - 'MailboxId' - 'InternetMessageId' - 'UserId' risk_score:25 security_domain:threat
