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P4T12ICK
82 lines
3.1 KiB
YAML
82 lines
3.1 KiB
YAML
name: Any Powershell DownloadString
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id: 4d015ef2-7adf-11eb-95da-acde48001122
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version: 1
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date: '2021-03-01'
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author: Michael Haag, Splunk
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type: TTP
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datamodel:
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- Endpoint
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description: The following analytic identifies the use of PowerShell downloading a
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file using `DownloadString` method. This particular method is utilized in many different
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PowerShell frameworks to download files and output to disk. Identify the source
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(IP/domain) and destination file and triage appropriately. If AMSI logging or PowerShell
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transaction logs are available, review for further details of the implant.
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
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as lastTime from datamodel=Endpoint.Processes where Processes.process_name=powershell.exe
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OR Processes.process_name=pwsh.exe OR Processes.process_name=PowerShell_ISE.exe
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Processes.process=*.DownloadString* by Processes.dest Processes.user Processes.parent_process
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Processes.process_name Processes.process Processes.process_id Processes.parent_process_id
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| `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)`|
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`any_powershell_downloadstring_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Processes` node.
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known_false_positives: False positives may be present and filtering will need to occur
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by parent process or command line argument. It may be required to modify this query
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to an EDR product for more granular coverage.
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references:
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- https://docs.microsoft.com/en-us/dotnet/api/system.net.webclient.downloadstring?view=net-5.0
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- https://blog.malwarebytes.com/malwarebytes-news/2021/02/lazyscripter-from-empire-to-double-rat/
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- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1059.001/T1059.001.md
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tags:
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analytic_story:
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- Malicious PowerShell
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- HAFNIUM Group
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- Ingress Tool Transfer
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automated_detection_testing: passed
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confidence: 70
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/atomic_red_team/windows-sysmon.log
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impact: 80
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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 $dest$ by user $user$. This behavior identifies the use of DownloadString
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within PowerShell.
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mitre_attack_id:
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- T1059.001
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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: Parent 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 Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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required_fields:
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- _time
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- Processes.process_name
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- Processes.process
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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.process_name
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- Processes.parent_process
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- Processes.process_id
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- Processes.parent_process_id
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risk_score: 56
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security_domain: endpoint
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