Name:Microsoft Defender ATP Alerts id:38f034ed-1598-46c8-95e8-14edf05fdf5d version:1 date:2024-10-30 author:Bryan Pluta, Bhavin Patel, Splunk status:production type:TTP Description:The following analytic is to leverage alerts from Microsoft Defender ATP Alerts. This query aggregates and summarizes all alerts from Microsoft Defender ATP Alerts, providing details such as the source, file name, severity, process command line, ip address, registry key, signature, description, unique id, and timestamps. This detection is not intended to detect new activity from raw data, but leverages Microsoft provided alerts to be correlated with other data as part of risk based alerting. The data contained in the alert is mapped not only to the risk obejct, but also the threat object. This detection filters out evidence that has a verdict of clean from Microsoft. It dynamically maps the MITRE technique at search time to auto populate the annotation field with the value provided in the alert. It also uses a dynamic mapping to set the risk score in Enterprise Security based on the severity of the alert. Data_source:
-MS Defender ATP Alerts
search: `ms_defender_atp_alerts` (dest=* OR user=*)| eval tmp_evidence=json_extract(_raw, "evidence"), tmp_evidencemv=json_array_to_mv(tmp_evidence), entityType = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "entityType")), filePath = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "filePath")), processCommandLine = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "processCommandLine")), ipAddress = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "ipAddress")), registryKey = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "registryKey")), url = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "url")), fileName = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "fileName")) | eval tmp_evidencemv=mvfilter(json_extract(tmp_evidencemv, "entityType") = "File"), fileName = mvmap(tmp_evidencemv, spath(tmp_evidencemv, "fileName")) | eval risk_score=case(severity="informational", 5, severity="low", 15, severity="medium", 25, severity="high", 50 , true(), 2) | eval processCommandLine=if(processCommandLine="null", "", processCommandLine), ipAddress=if(ipAddress="null", "", ipAddress), registryKey=if(registryKey="null", "", registryKey), url=if(url="null", "", url) | stats count min(_time) as firstTime max(_time) as lastTime values(fileName) as file_name values(severity) as severity values(processCommandLine) as process values(ipAddress) as ip_address values(registryKey) as registry_key values(url) as url values(mitreTechniques{}) as annotations.mitre_attack.mitre_technique_id values(signature) as signature values(user) as user values(risk_score) as risk_score by id description src | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `microsoft_defender_atp_alerts_filter`
how_to_implement:In order to properly run this search, you need to ingest alerts data from Microsoft Defender, specifcally using the Splunk add-on for Microsoft Security. This add-on will collect alerts using the ms:defender:atp:alerts sourcetype. You will need to define the `ms_defender_atp_alerts` macro to point to the proper index that contains the ms:defender:atp:alerts sourcetype. **NOTE** - We also have a detection named `Detect Critical Alerts from Security Tools` that triggers on the same data and is written against the Alerts datamodel. Enabling both of these detections will result in duplicate risk/notable events, we recommend enabling only one of these detections. known_false_positives:False positives may vary based on Microsfot Defender configuration; monitor and filter out the alerts that are not relevant to your environment. References: -https://learn.microsoft.com/en-us/defender-xdr/api-list-incidents?view=o365-worldwide -https://learn.microsoft.com/en-us/graph/api/resources/security-alert?view=graph-rest-1.0 -https://splunkbase.splunk.com/app/6207 -https://jasonconger.com/splunk-azure-gdi/ drilldown_searches: name:'View the detection results for - "$src$"' search:'%original_detection_search% | search src = "$src$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$src$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src$") 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: - 'Critical Alerts' asset_type:Endpoint atomic_guid: confidence:90 impact:90 message:$severity$ alert for $src$ - $signature$ mitre_attack_id: observable: name:'src' type:'Endpoint' - role: - 'Victim' name:'user' type:'User' - role: - 'Victim' name:'file_name' type:'File Name' - role: - 'Attacker' name:'process' type:'Process Name' - role: - 'Attacker' name:'ip_address' type:'IP Address' - role: - 'Attacker' name:'registry_key' type:'Registry Key' - role: - 'Attacker' name:'url' type:'URL String' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'entityType' - 'filePath' - 'processCommandLine' - 'ipAddress' - 'registryKey' - 'url' - 'fileName' - 'risk_score' - 'firstTime' - 'lastTime' - 'src' - 'severity' - 'annotations.mitre_attack' - 'signature' - 'user' risk_score:81 security_domain:endpoint manual_test:We are dynamically creating the risk_score field based on the severity of the alert in the SPL and that supersedes the risk score set in the detection. Setting these to manual test since otherwise we fail integration testing. The detection is also failing on unit-testing as some of the fields set in the observables are empty.
