Name:O365 Email Receive and Hard Delete Takeover Behavior id:b66aeaa4-586f-428b-8a2b-c4fd3039d8d3 version:1 date:2025-01-20 author:Steven Dick status:production type:Anomaly Description:The following analytic identifies when an O365 email recipient receives and then deletes emails related to password or banking/payroll changes within a short period. This behavior may indicate a compromised account where the threat actor is attempting to redirect the victims payroll to an attacker controlled bank account. Data_source:
-Office 365 Universal Audit Log
-Office 365 Reporting Message Trace
search:`o365_messagetrace` subject IN ("*banking*","*direct deposit*","*pay-to*","*password *","*passcode *","*OTP *","*MFA *","*Account Recovery*") | eval mailtime = _time | bin _time span=4hr | eval user = lower(RecipientAddress) | eval InternetMessageId = lower(MessageId) | join InternetMessageId, user max=0 [
| search `o365_management_activity` Workload=Exchange Operation IN ("HardDelete") AND Folder.Path IN ("\\Sent Items","\\Recoverable Items\\Deletions")
| eval InternetMessageId = lower(InternetMessageId), user = lower(UserId), subject = Subject ] | stats values(ClientIPAddress) as src, values(ClientInfoString) as http_user_agent, values(Folder.Path) as file_path, values(Operation) as signature, values(ResultStatus) as result, values(InternetMessageId) as signature_id, count, min(mailtime) as firstTime, max(deltime) as lastTime by user,subject | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `o365_email_receive_and_hard_delete_takeover_behavior_filter`
how_to_implement:You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events AND Message Trace events. known_false_positives:Possible new user/account onboarding processes. References: -https://attack.mitre.org/techniques/T1114/ -https://www.hhs.gov/sites/default/files/help-desk-social-engineering-sector-alert-tlpclear.pdf -https://intelligence.abnormalsecurity.com/attack-library/threat-actor-convincingly-impersonates-employee-requesting-direct-deposit-update-in-likely-ai-generated-attack drilldown_searches: name:'View the detection results for - "$user$"' search:'%original_detection_search% | search user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") 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:'$info_max_time$' name:'Investigate Email for $user$' search:'`o365_messagetrace` subject IN ("*banking*","*direct deposit*","*pay-to*","*password *","*passcode *","*OTP *","*MFA *","*Account Recovery*") AND RecipientAddress = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Office 365 Account Takeover' - 'Office 365 Collection Techniques' - 'Suspicious Emails' - 'Data Destruction' asset_type:O365 Tenant mitre_attack_id: - 'T1070.008' - 'T1485' - 'T1114.001' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:threat
