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https://github.com/splunk/security_content
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Michael Haag
62 lines
2.8 KiB
YAML
62 lines
2.8 KiB
YAML
name: Common Ransomware Notes
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id: ada0f478-84a8-4641-a3f1-d82362d6bd71
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version: 12
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date: '2025-10-14'
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author: David Dorsey, Splunk
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status: production
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type: Hunting
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description: The following analytic detects the creation of files with names commonly
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associated with ransomware notes. It leverages file-system activity data from the
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Endpoint Filesystem data model, typically populated by endpoint detection and response
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(EDR) tools or Sysmon logs. This activity is significant because ransomware notes
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indicate a potential ransomware attack, which can lead to data encryption and extortion.
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If confirmed malicious, this activity could result in significant data loss, operational
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disruption, and financial impact due to ransom demands.
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data_source:
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- Sysmon EventID 11
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
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as lastTime values(Filesystem.user) as user values(Filesystem.dest) as dest values(Filesystem.file_path)
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as file_path from datamodel=Endpoint.Filesystem by Filesystem.action Filesystem.dest
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Filesystem.file_access_time Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
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Filesystem.file_name Filesystem.file_path Filesystem.file_acl Filesystem.file_size
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Filesystem.process_guid Filesystem.process_id Filesystem.user Filesystem.vendor_product
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| `drop_dm_object_name(Filesystem)` | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)`
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| `ransomware_notes` | `common_ransomware_notes_filter`'
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how_to_implement: You must be ingesting data that records file-system activity from
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your hosts to populate the Endpoint Filesystem data-model node. This is typically
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populated via endpoint detection-and-response product, such as Carbon Black, or
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via other endpoint data sources, such as Sysmon. The data used for this search is
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typically generated via logs that report file-system reads and writes.
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known_false_positives: It's possible that a legitimate file could be created with
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the same name used by ransomware note files.
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references: []
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tags:
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analytic_story:
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- Chaos Ransomware
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- Rhysida Ransomware
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- Ransomware
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- LockBit Ransomware
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- Medusa Ransomware
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- SamSam Ransomware
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- Clop Ransomware
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- Ryuk Ransomware
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- Black Basta Ransomware
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- Termite Ransomware
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- Interlock Ransomware
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- NailaoLocker Ransomware
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- Hellcat Ransomware
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asset_type: Endpoint
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mitre_attack_id:
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- T1485
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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: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1485/ransomware_notes/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: XmlWinEventLog
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