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d1vious
86 lines
3.2 KiB
YAML
86 lines
3.2 KiB
YAML
name: Fsutil Zeroing File
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id: f792cdc9-43ee-4429-a3c0-ffce4fed1a85
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version: 1
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date: '2021-12-07'
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author: Michael Haag, Splunk
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type: TTP
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datamodel:
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- Endpoint_Processes
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description: This search is to detect a suspicious fsutil process to zeroing a target
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file. This technique was seen in lockbit ransomware where it tries to zero out its
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malware path as part of its defense evasion after encrypting the compromised host.
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search: '| from read_ssa_enriched_events() | eval timestamp=parse_long(ucast(map_get(input_event,
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"_time"), "string", null)), cmd_line=lower(ucast(map_get(input_event, "process"),
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"string", null)), process_name=lower(ucast(map_get(input_event, "process_name"),
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"string", null)), process_path=ucast(map_get(input_event, "process_path"), "string",
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null), parent_process_name=ucast(map_get(input_event, "parent_process_name"), "string",
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null), event_id=ucast(map_get(input_event, "event_id"), "string", null) | where
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cmd_line IS NOT NULL AND process_name IS NOT NULL AND process_name="fsutil.exe"
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AND (like (cmd_line, "%setzerodata%")) | eval start_time=timestamp, end_time=timestamp,
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entities=mvappend(ucast(map_get(input_event, "dest_user_id"), "string", null), ucast(map_get(input_event,
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"dest_device_id"), "string", null)), body=create_map(["event_id", event_id, "cmd_line",
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cmd_line, "process_name", process_name, "parent_process_name", parent_process_name,
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"process_path", process_path]) | into write_ssa_detected_events();'
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how_to_implement: To successfully implement this search, you need to be ingesting
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logs with the process name, parent process, and command-line executions from your
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endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the
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Sysmon TA. Tune and filter known instances where renamed net.exe may be used.
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known_false_positives: System administrators or scripts may delete user accounts via
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this technique. Filter as needed.
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references:
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- https://app.any.run/tasks/e0ac072d-58c9-4f53-8a3b-3e491c7ac5db/
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- https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-file
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tags:
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analytic_story:
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- Ransomware
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- Insider Threat
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- Information Sabotage
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cis20: []
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confidence: 90
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context:
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- Source:Endpoint
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- Stage:Defense Evasion
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1070/fsutil_file_zero/windows-security.log
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impact: 60
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kill_chain_phases:
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- Exploitation
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message: An instance of $parent_process_name$ spawning $process_name$ was identified
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on endpoint $dest_device_id$ by user $dest_user_id$ atempting to perform file
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deletion.
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mitre_attack_id:
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- T1070
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nist: []
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observable:
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- name: dest_user_id
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type: User
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role:
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- Victim
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- name: dest_device_id
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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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- Parent Process
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- name: process_name
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type: Process
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role:
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- Child Process
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product:
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- Splunk Behavioral Analytics
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required_fields:
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- _time
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- dest_device_id
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- process_name
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- parent_process_name
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- process_path
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- dest_user_id
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- process
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- cmd_line
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risk_score: 54
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risk_severity: medium
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security_domain: endpoint
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asset_type: Endpoint
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