Detection rules › Kusto

AWSGuardDuty - GuardDuty Alert

Status
available
Severity
medium
Time window
5h
Source
github.com/Azure/Azure-Sentinel

Identifies Amazon GuardDuty findings and creates a Microsoft Sentinel alert for each finding. Use the GuardDuty finding details in the alert to determine the specific malicious or suspicious activity that was detected.

Rule body kusto

id: bf0cde21-0c41-48f6-a40c-6b5bd71fa106
name: AWSGuardDuty - GuardDuty Alert
description: |
  Identifies Amazon GuardDuty findings and creates a Microsoft Sentinel alert for each finding. Use the GuardDuty finding details in the alert to determine the specific malicious or suspicious activity that was detected.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: AWSS3
    dataTypes:
      - AWSGuardDuty
queryFrequency: 5h
queryPeriod: 5h
triggerOperator: gt
triggerThreshold: 0
tactics: []
relevantTechniques: []
query: |
  // https://docs.aws.amazon.com/guardduty/latest/ug/guardduty_findings.html 
  AWSGuardDuty 
  // Parse the finding
  // https://docs.aws.amazon.com/guardduty/latest/ug/guardduty_finding-format.html 
  // Example: "ThreatPurpose:ResourceTypeAffected/ThreatFamilyName.DetectionMechanism!Artifact"
  | extend findingTokens = split(ActivityType, ":")
  | extend ThreatPurpose=findingTokens[0], findingTokens=split(findingTokens[1], "/")
  | extend ResourceTypeAffected=findingTokens[0], findingTokens= split(findingTokens[1], ".")
  | extend ThreatFamilyName=findingTokens[0], findingTokens=split(findingTokens[1], "!")
  | extend DetectionMechanism=findingTokens[0], Artifact=findingTokens[1]
  // Assign severity level
  // https://docs.aws.amazon.com/guardduty/latest/ug/guardduty_findings.html#guardduty_findings-severity
  | extend Severity = 
      case (
        Severity >= 7.0, "High",
        Severity between (4.0 .. 6.9), "Medium",
        Severity between (1.0 .. 3.9), "Low",
        "Unknown"
      )
  // Pull out any available resource details we can extract entities from. These may not exist in the alert.
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_Resource.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_AccessKeyDetails.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_RdsDbUserDetails.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_KubernetesDetails.html 
  | extend AccessKeyDetails=ResourceDetails.accessKeyDetails
  | extend RdsDbUserDetails=ResourceDetails.rdsDbUserDetails
  | extend KubernetesDetails=ResourceDetails.kubernetesDetails
  // Pull out any available action details we can extract entities from. These may not exist in the alert.
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_Action.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_AwsApiCallAction.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_KubernetesApiCallAction.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_NetworkConnectionAction.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_RdsLoginAttemptAction.html 
  | extend ServiceAction = 
      case(
        isnotempty(ServiceDetails.action.awsApiCallAction), ServiceDetails.action.awsApiCallAction,
        isnotempty(ServiceDetails.action.kubernetesApiCallAction), ServiceDetails.action.kubernetesApiCallAction,
        isnotempty(ServiceDetails.action.networkConnectionAction), ServiceDetails.action.networkConnectionAction,
        isnotempty(ServiceDetails.action.rdsLoginAttemptAction), ServiceDetails.action.rdsLoginAttemptAction,
        dynamic(null)
      )
  // The IPv4 remote address of the connection
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_RemoteIpDetails.html 
  // or
  // The IP of the Kubernetes API caller and the IPs of any proxies or load balancers between the caller and the API endpoint 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_KubernetesApiCallAction.html 
  | extend RemoteIpAddress = 
      coalesce(
        tostring(ServiceAction.remoteIpDetails.ipAddressV4),
        tostring(parse_json(ServiceAction.sourceIPs)[0])
      )
  // The IPv4 local address of the connection
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_LocalIpDetails.html 
  | extend LocalIpAddress = ServiceAction.localIpDetails.ipAddressV4
  // The AWS account ID of the remote API caller.
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_AwsApiCallAction.html 
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_RemoteAccountDetails.html 
  | extend RemoteAWSAccountId = ServiceAction.remoteAccountDetails.accountId
  // The IAM access key details (user information) of a user that engaged in the activity that prompted GuardDuty to generate a finding
  // https://docs.aws.amazon.com/guardduty/latest/APIReference/API_AccessKeyDetails.html 
  | extend AccountUpn = 
      case(
        AccessKeyDetails.userType == "IAMUser", AccessKeyDetails.userName,
        AccessKeyDetails.userType == "AssumedRole", split(AccessKeyDetails.principalId, ":", 1)[0],
        isnotempty(RdsDbUserDetails.user), RdsDbUserDetails.user,
        isnotempty(KubernetesDetails.kubernetesUserDetails.username), KubernetesDetails.kubernetesUserDetails.username,
        ""
      )
  | extend AccountName = split(AccountUpn, "@", 0)[0]
  | extend UPNSuffix = split(AccountUpn, "@", 1)[0]
  // Clean up the output
  | extend GuardDutyDetails =
      bag_pack( 
        "DetectorId", ServiceDetails.detectorId,
        "Partition", Partition,
        "Region", Region
      )
  | extend FindingLink = 
      iff(
        isnotempty(Region) and isnotempty(Id),
        strcat("https://", Region, ".console.aws.amazon.com/guardduty/home?region=", Region, "#/findings?fId=", Id),
        ""
      )
  | extend FindingLinkDescription = 
      iff(
        isnotempty(FindingLink),
        strcat("Link to GuardDuty finding (AWS): ", FindingLink),
        ""
      )
  | project-rename 
      FindingArn=Arn,
      FindingId=Id,
      AWSAccountId=AccountId
  | project-away 
      ActivityType, 
      findingTokens,
      Partition,
      Region, 
      SchemaVersion,
      TimeGenerated,
      Type
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: UPNSuffix
      - identifier: ObjectGuid
        columnName: RemoteAWSAccountId
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: RemoteIpAddress
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: LocalIpAddress
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: FindingLink
customDetails:
  ThreatPurpose: ThreatPurpose
  ResourceTypeAffected: ResourceTypeAffected
  ThreatFamilyName: ThreatFamilyName
  DetectionMechanism: DetectionMechanism
  Artifact: Artifact
alertDetailsOverride:
  alertDisplayNameFormat: '{{Title}}'
  alertDescriptionFormat: '{{Description}}'
  alertTacticsColumnName: ThreatPurpose
  alertSeverityColumnName: Severity
kind: Scheduled
version: 1.0.7

Stages and Predicates

Stage 1: source

AWSGuardDuty

Stage 2: extend (19 consecutive steps)

| extend findingTokens = split(ActivityType, ":")
| extend ThreatPurpose=findingTokens[0], findingTokens=split(findingTokens[1], "/")
| extend ResourceTypeAffected=findingTokens[0], findingTokens= split(findingTokens[1], ".")
| extend ThreatFamilyName=findingTokens[0], findingTokens=split(findingTokens[1], "!")
| extend DetectionMechanism=findingTokens[0], Artifact=findingTokens[1]
| extend Severity = 
    case (
      Severity >= 7.0, "High",
      Severity between (4.0 .. 6.9), "Medium",
      Severity between (1.0 .. 3.9), "Low",
      "Unknown"
    )
| extend AccessKeyDetails=ResourceDetails.accessKeyDetails
| extend RdsDbUserDetails=ResourceDetails.rdsDbUserDetails
| extend KubernetesDetails=ResourceDetails.kubernetesDetails
| extend ServiceAction = 
    case(
      isnotempty(ServiceDetails.action.awsApiCallAction), ServiceDetails.action.awsApiCallAction,
      isnotempty(ServiceDetails.action.kubernetesApiCallAction), ServiceDetails.action.kubernetesApiCallAction,
      isnotempty(ServiceDetails.action.networkConnectionAction), ServiceDetails.action.networkConnectionAction,
      isnotempty(ServiceDetails.action.rdsLoginAttemptAction), ServiceDetails.action.rdsLoginAttemptAction,
      dynamic(null)
    )
| extend RemoteIpAddress = 
    coalesce(
      tostring(ServiceAction.remoteIpDetails.ipAddressV4),
      tostring(parse_json(ServiceAction.sourceIPs)[0])
    )
| extend LocalIpAddress = ServiceAction.localIpDetails.ipAddressV4
| extend RemoteAWSAccountId = ServiceAction.remoteAccountDetails.accountId
| extend AccountUpn = 
    case(
      AccessKeyDetails.userType == "IAMUser", AccessKeyDetails.userName,
      AccessKeyDetails.userType == "AssumedRole", split(AccessKeyDetails.principalId, ":", 1)[0],
      isnotempty(RdsDbUserDetails.user), RdsDbUserDetails.user,
      isnotempty(KubernetesDetails.kubernetesUserDetails.username), KubernetesDetails.kubernetesUserDetails.username,
      ""
    )
| extend AccountName = split(AccountUpn, "@", 0)[0]
| extend UPNSuffix = split(AccountUpn, "@", 1)[0]
| extend GuardDutyDetails =
    bag_pack( 
      "DetectorId", ServiceDetails.detectorId,
      "Partition", Partition,
      "Region", Region
    )
| extend FindingLink = 
    iff(
      isnotempty(Region) and isnotempty(Id),
      strcat("https://", Region, ".console.aws.amazon.com/guardduty/home?region=", Region, "#/findings?fId=", Id),
      ""
    )
| extend FindingLinkDescription = 
    iff(
      isnotempty(FindingLink),
      strcat("Link to GuardDuty finding (AWS): ", FindingLink),
      ""
    )

Stage 3: project-rename

| project-rename 
    FindingArn=Arn,
    FindingId=Id,
    AWSAccountId=AccountId

Stage 4: project-away

| project-away 
    ActivityType, 
    findingTokens,
    Partition,
    Region, 
    SchemaVersion,
    TimeGenerated,
    Type

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
ThreatPurposeextend
ResourceTypeAffectedextend
ThreatFamilyNameextend
Artifactextend
DetectionMechanismextend
Severityextend
AccessKeyDetailsextend
RdsDbUserDetailsextend
KubernetesDetailsextend
ServiceActionextend
RemoteIpAddressextend
LocalIpAddressextend
RemoteAWSAccountIdextend
AccountUpnextend
AccountNameextend
UPNSuffixextend
GuardDutyDetailsextend
FindingLinkextend
FindingLinkDescriptionextend
AWSAccountIdproject-rename
FindingArnproject-rename
FindingIdproject-rename