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P4T12ICK
89 lines
3.0 KiB
YAML
89 lines
3.0 KiB
YAML
name: Any Powershell DownloadString
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id: 4d015ef2-7adf-11eb-95da-acde48001122
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version: 3
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date: '2022-04-07'
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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 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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data_source:
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- Sysmon Event ID 1
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search:
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selection1:
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OriginalFileName: pwsh.dll
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selection2:
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Image|endswith:
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- pwsh.exe
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- sqlps.exe
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- sqltoolsps.exe
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- powershell.exe
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- powershell_ise.exe
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selection3:
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OriginalFileName: PowerShell.EXE
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selection4:
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OriginalFileName: powershell_ise.EXE
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selection5:
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CommandLine: '*.DownloadString*'
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condition: (selection1 or selection2 or selection3 or selection4) and selection5
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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. In addition,
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confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
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endpoint product.
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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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- Hermetic Wiper
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- Malicious PowerShell
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- HAFNIUM Group
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- Ingress Tool Transfer
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asset_type: Endpoint
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confidence: 70
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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 $user$. 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
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- T1059.001
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- T1105
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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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- 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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risk_score: 56
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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/T1059.001/atomic_red_team/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: xmlwineventlog
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