Nterl0k - T1552 Suspect o365 Searches

detections/cloud/o365_email_suspicious_search_behavior.yml

@@ -0,0 +1,70 @@
+name: O365 Email Suspicious Search Behavior
+id: 3b6e1d36-6916-4eec-a7d5-bc98953ba595
+version: 1
+date: '2025-02-27'
+author: Steven Dick
+status: production
+type: Anomaly
+description: The following analytic identifies when Office 365 users search for suspicious keywords or have an excessive number of queries to a mailbox within a limited timeframe. This behavior may indicate that a malicious actor has gained control of a mailbox and is conducting discovery or enumeration activities.
+data_source: 
+- Office 365 Universal Audit Log
+search: |-
+  `o365_management_activity` Operation=SearchQueryInitiatedExchange
+  | eval command = case(Operation=="SearchQueryPerformed",SearchQueryText,true(),QueryText), UserId = lower(UserId), signature_id = CorrelationId, signature=Operation, src = ClientIP, user = lower(UserId), object_name=case(Operation=="SearchQueryPerformed",'EventData',true(),QuerySource), -time = _time, suspect_terms = case(match(command, `o365_suspect_search_terms_regex`),command,true(),null())
+  | where command != "*" AND command != "(*)" 
+  | bin _time span=1hr
+  | `o365_email_suspicious_search_behavior_filter`
+  | stats values(ScenarioName) as app, values(object_name) as object_name values(command) as command, values(suspect_terms) as suspect_terms, values(src) as src, dc(suspect_terms) as suspect_terms_count, dc(command) as count, min(-time) as firstTime, max(-time) as lastTime by user,signature,_time
+  | where count > 20 OR suspect_terms_count >= 2
+  | `security_content_ctime(firstTime)` 
+  | `security_content_ctime(lastTime)`
+how_to_implement: You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. You must also enable SearchQueryInitiated category as part of your organizations mailbox audit logging policy. The thresholds and match terms set within the analytic are initial guidelines and should be customized based on the organization's user behavior and risk profile. Security teams are encouraged to adjust these thresholds to optimize the balance between detecting genuine threats and minimizing false positives, ensuring the detection is tailored to their specific environment.
+known_false_positives: Users searching excessively or possible false positives related to matching conditions.
+references:
+- https://learn.microsoft.com/en-us/purview/audit-get-started#step-3-enable-searchqueryinitiated-events
+- https://www.cisa.gov/sites/default/files/2025-01/microsoft-expanded-cloud-logs-implementation-playbook-508c.pdf
+- https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-320a
+- https://attack.mitre.org/techniques/T1114/002/
+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 search behavior by $user$ 
+  search: '`o365_management_activity` AND Operation=SearchQueryInitiatedExchange AND UserId = "$user$"'
+  earliest_offset: $info_min_time$
+  latest_offset: $info_max_time$
+rba:
+  message: The user $user$ searched email suspiciously, $count$ unique terms and $suspect_terms_count$ suspect terms were searched within a limited timeframe.
+  risk_objects: 
+  - field: user
+    type: user
+    score: 35
+  threat_objects: 
+  - field: src
+    type: ip_address
+tags:
+  analytic_story: 
+  - Office 365 Account Takeover
+  - Office 365 Collection Techniques
+  - Compromised User Account
+  - CISA AA22-320A
+  asset_type: O365 Tenant
+  mitre_attack_id: 
+  - T1114.002 
+  - T1552
+  product: 
+  - Splunk Enterprise
+  - Splunk Enterprise Security
+  - Splunk Cloud
+  security_domain: threat
+tests:
+- name: True Positive Test
+  attack_data:
+  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1213.002/o365_sus_sharepoint_search/o365_sus_sharepoint_search.log
+    source: o365
+    sourcetype: o365:management:activity

detections/cloud/o365_sharepoint_suspicious_search_behavior.yml

@@ -1,26 +1,28 @@
 name: O365 SharePoint Suspicious Search Behavior
 id: 6ca919db-52f3-4c95-a4e9-7b189e8a043d
-version: 1
-date: '2025-01-08'
+version: 2
+date: '2025-02-27'
 author: Steven Dick
 status: production
 type: Anomaly
-description: The following analytic identifies when the O365 SharePoint users search for suspicious keywords or have an excessive number of queries within a limited timeframe. This behavior may indicate malicious actor enumeration of SharePoint based data within O365.
+description: The following analytic identifies when Office 365 users search for suspicious keywords or have an excessive number of queries to a SharePoint site within a limited timeframe. This behavior may indicate that a malicious actor has gained control of a user account and is conducting discovery or enumeration activities.
 data_source: 
 - Office 365 Universal Audit Log
 search: |-
-  `o365_management_activity` Workload=SharePoint Operation="SearchQueryPerformed" SearchQueryText=* EventData=*search*
-  | where NOT (match(SearchQueryText, "\*") OR match(SearchQueryText,"(\*)"))
-  | eval signature_id = CorrelationId, signature=Operation, src = ClientIP, user = UserId, object_name=EventData, command = SearchQueryText, -time = _time 
-  | bin _time span=1hr
-  | stats values(object_name) as object_name values(command) as command, values(src) as src, dc(command) as count, min(-time) as firstTime, max(-time) as lastTime by user,signature,_time
-  | where count > 20 OR match(command, "(?i)password|credential|passwd|shadow|active directory|account|username|network|computer|access|MFA|bank|deposit|payroll|EFT|Electonic Funds|routing")
-  | `security_content_ctime(firstTime)` 
-  | `security_content_ctime(lastTime)`
+  `o365_management_activity` (Workload=SharePoint Operation="SearchQueryPerformed" SearchQueryText=* EventData=*search*) OR Operation=SearchQueryInitiatedSharepoint 
+  | eval command = case(Operation=="SearchQueryPerformed",SearchQueryText,true(),QueryText), UserId = lower(UserId), signature_id = CorrelationId, signature=Operation, src = ClientIP, user = lower(UserId), object_name=case(Operation=="SearchQueryPerformed",'EventData',true(),QuerySource), -time = _time, suspect_terms = case(match(command, `o365_suspect_search_terms_regex`),command,true(),null()) 
+  | where command != "*" AND command != "(*)" 
+  | bin _time span=1hr 
   | `o365_sharepoint_suspicious_search_behavior_filter`
+  | stats values(ScenarioName) as app, values(object_name) as object_name values(command) as command, values(suspect_terms) as suspect_terms, values(src) as src, dc(suspect_terms) as suspect_terms_count, dc(command) as count, min(-time) as firstTime, max(-time) as lastTime by user,signature,_time 
+  | where count > 20 OR suspect_terms_count >= 2 
+  | `security_content_ctime(firstTime)` 
+  | `security_content_ctime(lastTime)` 
 how_to_implement: You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. The thresholds and match terms set within the analytic are initial guidelines and should be customized based on the organization's user behavior and risk profile. Security teams are encouraged to adjust these thresholds to optimize the balance between detecting genuine threats and minimizing false positives, ensuring the detection is tailored to their specific environment.
 known_false_positives: Users searching excessively or possible false positives related to matching conditions.
 references:
+- https://learn.microsoft.com/en-us/purview/audit-get-started#step-3-enable-searchqueryinitiated-events
+- https://www.cisa.gov/sites/default/files/2025-01/microsoft-expanded-cloud-logs-implementation-playbook-508c.pdf
 - https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-320a
 - https://attack.mitre.org/techniques/T1213/002/
 drilldown_searches:
@@ -33,22 +35,23 @@ drilldown_searches:
   earliest_offset: $info_min_time$
   latest_offset: $info_max_time$
 - name: Investigate search behavior by $user$ 
-  search: '`o365_management_activity` Workload=SharePoint Operation="SearchQueryPerformed" SearchQueryText=* EventData=*search* AND UserId = "$user$"'
+  search: '`o365_management_activity` (Workload=SharePoint Operation="SearchQueryPerformed" SearchQueryText=* EventData=*search* AND UserId = "$user$") OR (OR Operation=SearchQueryInitiatedSharepoint AND UserId = "$user$")'
   earliest_offset: $info_min_time$
   latest_offset: $info_max_time$
 rba:
-  message: The SharePoint Online was searched suspiciously by $user$
+  message: The user $user$ searched SharePoint suspiciously, $count$ unique terms and $suspect_terms_count$ suspect terms were searched within a limited timeframe.
   risk_objects:
   - field: user
     type: user
-    score: 25
+    score: 35
   threat_objects:
   - field: src
     type: ip_address
 tags:
   analytic_story: 
-  - Azure Active Directory Persistence
   - Office 365 Account Takeover
+  - Office 365 Collection Techniques
+  - Compromised User Account
   - CISA AA22-320A
   asset_type: O365 Tenant
   mitre_attack_id: 

macros/o365_suspect_search_terms_regex.yml

@@ -0,0 +1,3 @@
+definition: "\"(?i)password|credential|login|passwd|shadow|active directory|account|username|network|computer|access|MFA|bank|deposit|payroll|EFT|Electonic Funds|routing\""
+description: A regex used with match statements preloaded with generic suspicious terms or phrases. Is used to detect malicious actor or insider threat searches, replace/modify these terms to suit your organization.
+name: o365_suspect_search_terms_regex