GCP Audit Logs - VPC Flow Logs Disabled

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Id	8f3e9c2d-5b4a-4d6e-9a7c-2f8b5e1d3c9a
Rulename	GCP Audit Logs - VPC Flow Logs Disabled
Description	Detects when Google Cloud Platform VPC Flow Logs configurations are disabled or deleted. VPC Flow Logs capture information about IP traffic going to and from network interfaces in VPC networks, providing critical visibility for security monitoring and forensic analysis. Disabling VPC Flow Logs reduces network visibility and may indicate an attempt to evade detection before performing malicious activities. Adversaries may disable flow logs to hide lateral movement, data exfiltration, or command and control traffic.
Severity	High
Tactics	DefenseEvasion
Techniques	T1562.001
Required data connectors	GCPAuditLogsDefinition
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Google Cloud Platform Audit Logs/Analytic Rules/GCPVpcFlowLogsDisabled.yaml
Version	1.0.0
Arm template	8f3e9c2d-5b4a-4d6e-9a7c-2f8b5e1d3c9a.json

KQL

GCPAuditLogs
| where ServiceName == "networkmanagement.googleapis.com"
| where MethodName has_any ("VpcFlowLogsService.UpdateVpcFlowLogsConfig", "VpcFlowLogsService.DeleteVpcFlowLogsConfig")
| extend 
    RequestJson = parse_json(Request),
    RequestMetadataJson = parse_json(RequestMetadata),
    AuthInfoJson = parse_json(AuthenticationInfo),
    AuthzInfoJson = parse_json(AuthorizationInfo)
| extend 
    FlowLogsConfigName = split(GCPResourceName, "/")[-1],
    ConfigState = tostring(RequestJson.vpc_flow_logs_config.state),
    CallerIpAddress = tostring(RequestMetadataJson.callerIp),
    AuthEmail = tostring(AuthInfoJson.principalEmail),
    Permission = tostring(AuthzInfoJson[0].permission),
    PermissionType = tostring(AuthzInfoJson[0].permissionType),
    PermissionGranted = tostring(AuthzInfoJson[0].granted)
| where PermissionType == "ADMIN_WRITE"
| where MethodName has "DeleteVpcFlowLogsConfig" or ConfigState == "DISABLED"
| extend 
    Action = case(
        MethodName has "DeleteVpcFlowLogsConfig", "Deleted",
        ConfigState == "DISABLED", "Disabled",
        "Modified"),
    AccountName = tostring(split(PrincipalEmail, "@")[0]), 
    AccountUPNSuffix = tostring(split(PrincipalEmail, "@")[1])
| project TimeGenerated,
          PrincipalEmail,
          AuthEmail,
          ProjectId,
          ResourceName = GCPResourceName,
          FlowLogsConfigName,
          Action,
          CallerIpAddress,
          MethodName,
          ServiceName,
          Severity,
          Permission,
          PermissionGranted,
          LogName,
          InsertId,
          AccountName,
          AccountUPNSuffix

YAML

name: GCP Audit Logs - VPC Flow Logs Disabled
query: |
  GCPAuditLogs
  | where ServiceName == "networkmanagement.googleapis.com"
  | where MethodName has_any ("VpcFlowLogsService.UpdateVpcFlowLogsConfig", "VpcFlowLogsService.DeleteVpcFlowLogsConfig")
  | extend 
      RequestJson = parse_json(Request),
      RequestMetadataJson = parse_json(RequestMetadata),
      AuthInfoJson = parse_json(AuthenticationInfo),
      AuthzInfoJson = parse_json(AuthorizationInfo)
  | extend 
      FlowLogsConfigName = split(GCPResourceName, "/")[-1],
      ConfigState = tostring(RequestJson.vpc_flow_logs_config.state),
      CallerIpAddress = tostring(RequestMetadataJson.callerIp),
      AuthEmail = tostring(AuthInfoJson.principalEmail),
      Permission = tostring(AuthzInfoJson[0].permission),
      PermissionType = tostring(AuthzInfoJson[0].permissionType),
      PermissionGranted = tostring(AuthzInfoJson[0].granted)
  | where PermissionType == "ADMIN_WRITE"
  | where MethodName has "DeleteVpcFlowLogsConfig" or ConfigState == "DISABLED"
  | extend 
      Action = case(
          MethodName has "DeleteVpcFlowLogsConfig", "Deleted",
          ConfigState == "DISABLED", "Disabled",
          "Modified"),
      AccountName = tostring(split(PrincipalEmail, "@")[0]), 
      AccountUPNSuffix = tostring(split(PrincipalEmail, "@")[1])
  | project TimeGenerated,
            PrincipalEmail,
            AuthEmail,
            ProjectId,
            ResourceName = GCPResourceName,
            FlowLogsConfigName,
            Action,
            CallerIpAddress,
            MethodName,
            ServiceName,
            Severity,
            Permission,
            PermissionGranted,
            LogName,
            InsertId,
            AccountName,
            AccountUPNSuffix  
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: PrincipalEmail
    identifier: FullName
  - columnName: AccountName
    identifier: Name
  - columnName: AccountUPNSuffix
    identifier: UPNSuffix
- entityType: IP
  fieldMappings:
  - columnName: CallerIpAddress
    identifier: Address
- entityType: CloudApplication
  fieldMappings:
  - columnName: ProjectId
    identifier: Name
  - columnName: ResourceName
    identifier: InstanceName
queryPeriod: 1h
version: 1.0.0
tactics:
- DefenseEvasion
triggerOperator: gt
kind: Scheduled
triggerThreshold: 0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Google Cloud Platform Audit Logs/Analytic Rules/GCPVpcFlowLogsDisabled.yaml
alertDetailsOverride:
  alertDescriptionFormat: |-
    GCP VPC Flow Logs configuration {{FlowLogsConfigName}} {{Action}} in project {{ProjectId}}.
    This action reduces network traffic visibility and may indicate an attempt to evade detection.    
    Investigate immediately to determine if this action was authorized and assess the security implications.
    Review recent network activity before the logs were disabled for signs of malicious behavior.    
  alertDisplayNameFormat: GCP VPC Flow Logs {{FlowLogsConfigName}} {{Action}} by {{PrincipalEmail}}
relevantTechniques:
- T1562.001
id: 8f3e9c2d-5b4a-4d6e-9a7c-2f8b5e1d3c9a
tags:
- GCP
- VPC Flow Logs
- Network Security
severity: High
requiredDataConnectors:
- connectorId: GCPAuditLogsDefinition
  dataTypes:
  - GCPAuditLogs
status: Available
description: |
  'Detects when Google Cloud Platform VPC Flow Logs configurations are disabled or deleted.
  VPC Flow Logs capture information about IP traffic going to and from network interfaces in VPC networks, providing critical visibility for security monitoring and forensic analysis.
  Disabling VPC Flow Logs reduces network visibility and may indicate an attempt to evade detection before performing malicious activities.
  Adversaries may disable flow logs to hide lateral movement, data exfiltration, or command and control traffic.'  
customDetails:
  Permission: Permission
  Action: Action
  ProjectId: ProjectId
  ResourceName: ResourceName
  FlowLogsConfigName: FlowLogsConfigName
queryFrequency: 1h

ARM