Remote File Creation with PsExec

id: 35ab0d58-baab-4154-87ed-fa2f69797e9e
name: Remote File Creation with PsExec
description: |
  This query was originally published in the threat analytics report, Ryuk ransomware. There is also a related blog.
  Ryuk is human-operated ransomware. Much like DoppelPaymer ransomware, Ryuk is spread manually, often on networks that are already infected with Trickbot.
  Ryuk operators use PsExec to manually spread the ransomware to other devices.
  The following query detects remote file creation events that might indicate an active attack.
  The See also section below lists links to other queries associated with Ryuk ransomware.
  References:
  https://www.microsoft.com/security/blog/2020/03/05/human-operated-ransomware-attacks-a-preventable-disaster/
  https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=Ransom:Win32/Ryuk.AA
  https://www.microsoft.com/security/blog/2020/03/05/human-operated-ransomware-attacks-a-preventable-disaster/
  https://docs.microsoft.com/sysinternals/downloads/psexec
severity: High
status: Available
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceFileEvents
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - LateralMovement
relevantTechniques:
  - T1570
tags:
  - Ryuk
  - Ransomware
  - PsExec
query: |
  // Find PsExec creating multiple files on remote machines in a 10-minute window
  DeviceFileEvents
  // Looking for PsExec by accepteula command flag
  | where InitiatingProcessCommandLine has "accepteula"
  // Remote machines and file is exe
  | where FolderPath has "\\\\" and FileName endswith ".exe"
  | extend Exe = countof(InitiatingProcessCommandLine, ".exe")
  // Checking to see if command line has 2 .exe or .bat
  | where InitiatingProcessCommandLine !has ".ps1" and Exe > 1 or
  InitiatingProcessCommandLine has ".bat"
  // Exclusions: Remove the following line to widen scope of AHQ
  | where not(InitiatingProcessCommandLine has_any("batch", "auditpol",
  "script", "scripts", "illusive", "rebootrequired"))
  | summarize FileCount = dcount(FolderPath), make_set(SHA1, 100000), make_set(FolderPath, 100000),
  make_set(FileName, 100000), make_set(InitiatingProcessCommandLine, 100000) by DeviceId, DeviceName,
  TimeWindow=bin(TimeGenerated, 10m), InitiatingProcessFileName
  | where FileCount > 4
  | extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
  | extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
version: 1.0.0
kind: Scheduled