NRT Base64 Encoded Windows Process Command-lines

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Id	c3e5dbaa-a540-408c-8b36-68bdfb3df088
Rulename	NRT Base64 Encoded Windows Process Command-lines
Description	This detection identifies instances of a base64 encoded PE file header seen in the process command line parameter.
Severity	Medium
Tactics	Execution DefenseEvasion
Techniques	T1059 T1027 T1140
Required data connectors	SecurityEvents WindowsSecurityEvents
Kind	NRT
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Security Events/Analytic Rules/NRT_base64_encoded_pefile.yaml
Version	1.0.2
Arm template	c3e5dbaa-a540-408c-8b36-68bdfb3df088.json

KQL

SecurityEvent
 | where EventID == 4688
 | where isnotempty(CommandLine)
 | where CommandLine contains "TVqQAAMAAAAEAAA"
 | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))

YAML

status: Available
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Security Events/Analytic Rules/NRT_base64_encoded_pefile.yaml
query: |
  SecurityEvent
   | where EventID == 4688
   | where isnotempty(CommandLine)
   | where CommandLine contains "TVqQAAMAAAAEAAA"
   | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))  
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvent
  connectorId: WindowsSecurityEvents
tactics:
- Execution
- DefenseEvasion
kind: NRT
name: NRT Base64 Encoded Windows Process Command-lines
relevantTechniques:
- T1059
- T1027
- T1140
severity: Medium
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: SubjectAccount
  - identifier: Name
    columnName: SubjectUserName
  - identifier: NTDomain
    columnName: SubjectDomainName
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: Computer
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
  entityType: Host
description: |
    'This detection identifies instances of a base64 encoded PE file header seen in the process command line parameter.'
version: 1.0.2
id: c3e5dbaa-a540-408c-8b36-68bdfb3df088

ARM