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

id: 432996e9-8a93-4407-985f-13707b318a0b
name: TI map File Hash to CommonSecurityLog Event
description: |
  'Identifies a match in CommonSecurityLog Event data from any FileHash IOC from TI'
severity: Medium
requiredDataConnectors:
  - connectorId: PaloAltoNetworks
    dataTypes:
      - CommonSecurityLog
  - 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;
  let fileHashIndicators = 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)
  | extend IndicatorId = tostring(split(Id, "--")[2])
  | extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
  | where isnotempty(FileHashValue)
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
  | where IsActive == true and ValidUntil > now();
  // Handle matches against both lower case and uppercase versions of the hash:
  (fileHashIndicators | extend  FileHashValue = tolower(FileHashValue)
  | union (fileHashIndicators | extend FileHashValue = toupper(FileHashValue)))
  | 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 (
    CommonSecurityLog | where TimeGenerated >= ago(dt_lookBack)
    | where isnotempty(FileHash)
    | extend CommonSecurityLog_TimeGenerated = TimeGenerated
    )
  on $left.FileHashValue == $right.FileHash
  | where CommonSecurityLog_TimeGenerated < ValidUntil
  | summarize CommonSecurityLog_TimeGenerated = arg_max(CommonSecurityLog_TimeGenerated, *) by IndicatorId, FileHashValue
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project CommonSecurityLog_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence,
  SourceIP, SourcePort, DestinationIP, DestinationPort, SourceUserID, SourceUserName, DeviceName, DeviceAction,
  RequestURL, DestinationUserName, DestinationUserID, ApplicationProtocol, Activity, FileHashValue, FileHashType, Url
  | extend HostName = tostring(split(DeviceName, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(DeviceName, '.'), 1, -1), '.'))
  | extend Name = tostring(split(SourceUserName, '@', 0)[0]), UPNSuffix = tostring(split(SourceUserName, '@', 1)[0])
  | extend timestamp = CommonSecurityLog_TimeGenerated
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: SourceUserName
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix 
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIP
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
  - entityType: FileHash
    fieldMappings:
      - identifier: Value
        columnName: FileHashValue
      - identifier: Algorithm
        columnName: FileHashType
version: 1.3.7
kind: Scheduled