Solutions/Threat Intelligence (NEW)/Analytic Rules/FileHashEntity_SecurityEvent.yaml

id: 9f7dc779-1e51-4925-ae4a-db1db933077f
name: TI map File Hash to Security Event
description: |
  'Identifies a match in Security Event data from any File Hash IOC from TI'
severity: Medium
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvents
  - connectorId: WindowsForwardedEvents
    dataTypes:
      - WindowsEvent
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  ThreatIntelIndicators
  //extract key part of kv pair
        | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
        | where isnotempty(IndicatorType) and IndicatorType == "file"
        | extend FileHashType = replace("'", "", substring(ObservableKey, indexof(ObservableKey, "hashes.") + 7, strlen(ObservableKey) - indexof(ObservableKey, "hashes.") - 7))
        | extend FileHashValue = toupper(ObservableValue)
  | where isnotempty(FileHashValue)
  | where TimeGenerated >= ago(ioc_lookBack)
  | extend FileHashValue = toupper(FileHashValue)
  | extend IndicatorId = tostring(split(Id, "--")[2])
  | extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
  | where IsActive == true and ValidUntil > now()
    | project-reorder *, FileHashType, FileHashValue, Type
  // using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
  | join kind=innerunique ( union isfuzzy=true
    (SecurityEvent | where TimeGenerated >= ago(dt_lookBack)
        | where EventID in ("8003","8002","8005")
        | where isnotempty(FileHash)
        | extend SecurityEvent_TimeGenerated = TimeGenerated, Event = EventID, FileHash = toupper(FileHash)
    ),
    (WindowsEvent | where TimeGenerated >= ago(dt_lookBack)
        | where EventID in ("8003","8002","8005")
        | where isnotempty(EventData.FileHash)
        | extend SecurityEvent_TimeGenerated = TimeGenerated, Event = EventID, FileHash = toupper(EventData.FileHash)
    )
  )
  on $left.FileHashValue == $right.FileHash
  | where SecurityEvent_TimeGenerated < ValidUntil
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | summarize SecurityEvent_TimeGenerated = arg_max(SecurityEvent_TimeGenerated, *) by IndicatorId, FileHash
  | project SecurityEvent_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ValidUntil, Confidence,
  Process, FileHash, Computer, Account, Event, FileHashValue, FileHashType, Url
  | extend NTDomain = tostring(split(Account, '\\', 0)[0]), Name = tostring(split(Account, '\\', 1)[0])
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.')) 
  | extend timestamp = SecurityEvent_TimeGenerated
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: Name
      - identifier: NTDomain
        columnName: NTDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
  - entityType: FileHash
    fieldMappings:
      - identifier: Value
        columnName: FileHashValue
      - identifier: Algorithm
        columnName: FileHashType
version: 1.4.7
kind: Scheduled