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Eric
90 lines
4.3 KiB
YAML
90 lines
4.3 KiB
YAML
name: Excel Spawning PowerShell
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id: 42d40a22-9be3-11eb-8f08-acde48001122
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version: 9
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date: '2025-02-10'
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author: Michael Haag, Splunk
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status: removed
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type: TTP
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description: The following analytic has been deprecated in favour of a more generic
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approach in "Windows Office Product Spawned Uncommon Process". The following analytic
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detects Microsoft Excel spawning PowerShell, an uncommon and suspicious behavior.
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This detection leverages data from Endpoint Detection and Response (EDR) agents,
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focusing on process creation events where the parent process is "excel.exe" and
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the child process is PowerShell. This activity is significant because it is often
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associated with spearphishing attacks, where malicious attachments execute encoded
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PowerShell commands. If confirmed malicious, this behavior could allow an attacker
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to execute arbitrary code, potentially leading to data exfiltration, privilege escalation,
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or persistent access within the environment.
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data_source:
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- Sysmon EventID 1
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- Windows Event Log Security 4688
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- CrowdStrike ProcessRollup2
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search: '| tstats `security_content_summariesonly` count values(Processes.process)
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min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes
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where Processes.parent_process_name="excel.exe" `process_powershell` by Processes.parent_process
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Processes.parent_process_name Processes.process_name Processes.user Processes.dest
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Processes.original_file_name | `drop_dm_object_name("Processes")` | `security_content_ctime(firstTime)`|`security_content_ctime(lastTime)`
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| `excel_spawning_powershell_filter`'
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how_to_implement: The detection is based on data that originates from Endpoint Detection
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and Response (EDR) agents. These agents are designed to provide security-related
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telemetry from the endpoints where the agent is installed. To implement this search,
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you must ingest logs that contain the process GUID, process name, and parent process.
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Additionally, you must ingest complete command-line executions. These logs must
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be processed using the appropriate Splunk Technology Add-ons that are specific to
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the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint`
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data model. Use the Splunk Common Information Model (CIM) to normalize the field
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names and speed up the data modeling process.
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known_false_positives: False positives should be limited, but if any are present,
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filter as needed.
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references:
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- https://redcanary.com/threat-detection-report/techniques/powershell/
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- https://attack.mitre.org/techniques/T1566/001/
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drilldown_searches:
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- name: View the detection results for - "$user$" and "$dest$"
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search: '%original_detection_search% | search user = "$user$" dest = "$dest$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$user$" and "$dest$"
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search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$",
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"$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time)
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as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk
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Message" values(analyticstories) as "Analytic Stories" values(annotations._all)
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as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics"
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by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: An instance of $parent_process_name$ spawning $process_name$ was identified
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on endpoint $dest$ by user $user$, indicating potential suspicious macro execution.
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risk_objects:
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- field: user
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type: user
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score: 80
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- field: dest
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type: system
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score: 80
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threat_objects:
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- field: parent_process_name
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type: parent_process_name
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- field: process_name
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type: process_name
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tags:
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analytic_story:
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- Spearphishing Attachments
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- Compromised Windows Host
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asset_type: Endpoint
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mitre_attack_id:
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- T1003.002
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data:
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https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566.001/macro/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: XmlWinEventLog
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