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ljstella
93 lines
3.7 KiB
YAML
93 lines
3.7 KiB
YAML
name: Excel Spawning PowerShell
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id: 42d40a22-9be3-11eb-8f08-acde48001122
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version: 4
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date: '2024-08-14'
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author: Michael Haag, Splunk
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status: production
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type: TTP
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description: The following analytic detects Microsoft Excel spawning PowerShell, an
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uncommon and suspicious behavior. This detection leverages data from Endpoint Detection
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and Response (EDR) agents, focusing on process creation events where the parent
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process is "excel.exe" and the child process is PowerShell. This activity is significant
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because it is often associated with spearphishing attacks, where malicious attachments
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execute encoded PowerShell commands. If confirmed malicious, this behavior could
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allow an attacker to execute arbitrary code, potentially leading to data exfiltration,
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privilege escalation, 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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tags:
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analytic_story:
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- Spearphishing Attachments
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asset_type: Endpoint
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confidence: 100
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impact: 80
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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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mitre_attack_id:
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- T1003.002
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- T1003
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observable:
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- name: user
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type: User
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role:
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- Victim
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- name: dest
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type: Hostname
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role:
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- Victim
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- name: parent_process_name
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type: Process
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role:
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- Attacker
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- name: process_name
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type: Process
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role:
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- Attacker
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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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required_fields:
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- Processes.dest
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- Processes.user
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- Processes.parent_process_name
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- Processes.parent_process
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- Processes.original_file_name
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- Processes.process_name
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- Processes.process
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- Processes.process_id
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- Processes.parent_process_path
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- Processes.process_path
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- Processes.parent_process_id
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risk_score: 80
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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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