mirror of
https://github.com/splunk/security_content
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Eric McGinnis
81 lines
3.8 KiB
YAML
81 lines
3.8 KiB
YAML
name: Common Ransomware Notes
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id: ada0f478-84a8-4641-a3f1-d82362d6bd71
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version: 15
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creation_date: '2019-10-16'
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modification_date: '2026-05-13'
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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: |
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The following analytic detects the creation of files with names commonly associated with ransomware notes.
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It leverages file-system activity data from the Endpoint Filesystem data model, typically populated by endpoint detection and response (EDR) tools or Sysmon logs.
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This activity is significant because ransomware notes 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 disruption, and financial impact due to ransom demands.
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Note that this analytic relies on a lookup table (ransomware_notes_lookup) that contains known ransomware note file names.
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Ensure that this lookup table is regularly updated to include new ransomware note file names as they are identified in the threat landscape.
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Also this analytic leverages a sub-search to enhance performance. sub-searches have limitations on the amount of data they can return. Keep this in mind if you have an extensive list of ransomware note file names.
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data_source:
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- Sysmon EventID 11
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search: |
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| tstats `security_content_summariesonly`
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count
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min(_time) as firstTime
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max(_time) as lastTime
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values(Filesystem.user) as user
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values(Filesystem.dest) as dest
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values(Filesystem.file_path) as file_path
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from datamodel=Endpoint.Filesystem
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where [
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| inputlookup ransomware_notes_lookup
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| search status=true
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| fields ransomware_notes
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| dedup ransomware_notes
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| rename ransomware_notes as Filesystem.file_name
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]
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by Filesystem.action Filesystem.dest Filesystem.file_access_time
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Filesystem.file_create_time Filesystem.file_hash
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Filesystem.file_modify_time Filesystem.file_name
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Filesystem.file_path Filesystem.file_acl Filesystem.file_size
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Filesystem.process_guid Filesystem.process_id Filesystem.user
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Filesystem.vendor_product
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| `drop_dm_object_name(Filesystem)`
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| `security_content_ctime(lastTime)`
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| `security_content_ctime(firstTime)`
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| `common_ransomware_notes_filter`
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how_to_implement: You must be ingesting data that records file-system activity from your hosts to populate the Endpoint Filesystem data-model node. This is typically populated via endpoint detection-and-response product, such as Carbon Black, or via other endpoint data sources, such as Sysmon. The data used for this search is typically generated via logs that report file-system reads and writes.
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known_false_positives: |
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There could be cases where a legitimate file coincidentally matches a known ransomware note
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name. In such cases, further investigation is required to determine the nature of the file and its context.
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references: []
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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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- Storm-0501 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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category: endpoint
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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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test_type: unit
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