Identify SysAid Server web shell creation

id: 50eb4cbd-188f-44f4-b964-bab84dcdec10
name: Identify SysAid Server web shell creation 
description: |
  'This query looks for potential webshell creation by the threat actor Mercury after the sucessful exploitation of SysAid server. 
  Reference:  https://www.microsoft.com/security/blog/2022/08/25/mercury-leveraging-log4j-2-vulnerabilities-in-unpatched-systems-to-target-israeli-organizations/'
severity: High
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent 
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent 
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceFileEvents
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
tags:
  - Mercury
  - Schema: ASIMFileEvent
    SchemaVersion: 0.1.0
query: |
  let timeframe = 1d;
  let time_window = 5m;
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated > ago(timeframe)
  | where EventID == 4688
  | where Process has_any ("java.exe", "javaw.exe") and CommandLine has "SysAidServer" 
  | summarize by ParentProcessName,Process, Account, Computer, CommandLine, timekey= bin(TimeGenerated, time_window), TimeGenerated, SubjectLogonId
  | join kind=inner(
  SecurityEvent
  | where TimeGenerated > ago(timeframe)
  | where EventID == 4663
  | where Process has_any ("java.exe", "javaw.exe")
  | where AccessMask in ('0x2','0x100', '0x10', '0x4')
  | where ObjectName endswith ".jsp" 
  | summarize by ParentProcessName, Account, Computer, ObjectName, ProcessName, timekey= bin(TimeGenerated, time_window), TimeGenerated, SubjectLogonId)
   on timekey, Computer, SubjectLogonId
  ),
  (DeviceFileEvents 
  | where InitiatingProcessFileName has_any ("java.exe", "javaw.exe")  
  | where InitiatingProcessCommandLine has "SysAidServer"  
  | where FileName endswith ".jsp" 
  | extend Account = strcat(InitiatingProcessAccountDomain, @'\', InitiatingProcessAccountName), Computer = DeviceName
  ),
  (imFileEvent
  | where TimeGenerated > ago(timeframe)
  | where EventType == "FileCreated"
  | where ActingProcessName has_any ("java.exe", "javaw.exe") 
  | where ActingProcessCommandLine has "SysAidServer"  
  | where FilePath endswith ".jsp" 
  | extend Account = ActorUsername, Computer = DvcHostname
  )
  )
  | extend AccountName = tostring(split(Account, @'\')[1]), AccountNTDomain = tostring(split(Account, @'\')[0])
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountNTDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
version: 1.0.3
kind: Scheduled
metadata:
    source:
        kind: Scheduled
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Others" ]