gcp-audit-logs

What this skill does

# GCP Audit Logs

Audit GCP activity with Cloud Audit Logs for compliance, security investigation, and operational monitoring.

## When to Use

- Enabling organization-wide audit logging across GCP projects
- Meeting compliance requirements for SOC 2, HIPAA, PCI DSS, or FedRAMP
- Investigating unauthorized access or suspicious API activity
- Setting up alerting on administrative and data access events
- Exporting logs to BigQuery for long-term analysis and reporting

## Audit Log Types

```yaml
log_types:
  admin_activity:
    description: API calls that modify resource configuration or metadata
    enabled: Always (cannot be disabled)
    retention: 400 days (default)
    cost: No charge
    examples:
      - Creating or deleting VM instances
      - Changing IAM policies
      - Modifying firewall rules

  data_access:
    description: API calls that read resource configuration, metadata, or user data
    enabled: Must be explicitly enabled (except BigQuery)
    retention: 30 days (default)
    cost: Can be significant at high volume
    subtypes:
      ADMIN_READ: Read resource configuration/metadata
      DATA_READ: Read user-provided data
      DATA_WRITE: Write user-provided data

  system_event:
    description: Actions performed by GCP systems on behalf of resources
    enabled: Always (cannot be disabled)
    retention: 400 days (default)
    cost: No charge
    examples:
      - Live migration of VM instances
      - Automatic scaling events

  policy_denied:
    description: Actions denied by VPC Service Controls or organization policies
    enabled: Always (cannot be disabled)
    retention: 400 days (default)
    cost: No charge
```

## Enable Data Access Logs for an Organization

```bash
# Get current org IAM policy
gcloud organizations get-iam-policy ORG_ID --format=json > org-policy.json

# Add audit config to org-policy.json:
# {
#   "auditConfigs": [
#     {
#       "service": "allServices",
#       "auditLogConfigs": [
#         {"logType": "ADMIN_READ"},
#         {"logType": "DATA_READ"},
#         {"logType": "DATA_WRITE"}
#       ]
#     }
#   ],
#   ...existing bindings...
# }

# Apply the updated policy
gcloud organizations set-iam-policy ORG_ID org-policy.json

# Enable data access logs for specific services at project level
gcloud projects get-iam-policy PROJECT_ID --format=json > project-policy.json

# Example: enable only for Cloud Storage and BigQuery
# {
#   "auditConfigs": [
#     {
#       "service": "storage.googleapis.com",
#       "auditLogConfigs": [
#         {"logType": "DATA_READ"},
#         {"logType": "DATA_WRITE"}
#       ]
#     },
#     {
#       "service": "bigquery.googleapis.com",
#       "auditLogConfigs": [
#         {"logType": "DATA_READ"},
#         {"logType": "DATA_WRITE"}
#       ]
#     }
#   ]
# }

gcloud projects set-iam-policy PROJECT_ID project-policy.json
```

## Configure Log Sinks for Export

```bash
# Create BigQuery dataset for audit log export
bq mk --dataset \
  --description "Audit log export" \
  --default_table_expiration 0 \
  --location US \
  PROJECT_ID:audit_logs

# Create organization-level log sink to BigQuery
gcloud logging sinks create org-audit-bigquery \
  bigquery.googleapis.com/projects/PROJECT_ID/datasets/audit_logs \
  --organization=ORG_ID \
  --include-children \
  --log-filter='logName:"cloudaudit.googleapis.com"'

# Get the sink writer identity and grant BigQuery access
SINK_SA=$(gcloud logging sinks describe org-audit-bigquery \
  --organization=ORG_ID --format='value(writerIdentity)')

bq add-iam-policy-binding \
  --member="$SINK_SA" \
  --role="roles/bigquery.dataEditor" \
  PROJECT_ID:audit_logs

# Create Cloud Storage sink for long-term archive
gsutil mb -l US -b on gs://org-audit-logs-archive
gsutil retention set 7y gs://org-audit-logs-archive

gcloud logging sinks create org-audit-storage \
  storage.googleapis.com/org-audit-logs-archive \
  --organization=ORG_ID \
  --include-children \
  --log-filter='logName:"cloudaudit.googleapis.com"'

STORAGE_SA=$(gcloud logging sinks describe org-audit-storage \
  --organization=ORG_ID --format='value(writerIdentity)')

gsutil iam ch "$STORAGE_SA:objectCreator" gs://org-audit-logs-archive

# Create Pub/Sub sink for real-time streaming to SIEM
gcloud pubsub topics create audit-log-stream

gcloud logging sinks create org-audit-pubsub \
  pubsub.googleapis.com/projects/PROJECT_ID/topics/audit-log-stream \
  --organization=ORG_ID \
  --include-children \
  --log-filter='logName:"cloudaudit.googleapis.com" AND (protoPayload.methodName:"delete" OR protoPayload.methodName:"setIamPolicy" OR severity>=WARNING)'

PUBSUB_SA=$(gcloud logging sinks describe org-audit-pubsub \
  --organization=ORG_ID --format='value(writerIdentity)')

gcloud pubsub topics add-iam-policy-binding audit-log-stream \
  --member="$PUBSUB_SA" \
  --role="roles/pubsub.publisher"
```

## Logging Queries (Cloud Logging Explorer)

```bash
# View admin activity logs for the last 24 hours
gcloud logging read 'logName:"cloudaudit.googleapis.com/activity"
  AND timestamp>="2024-01-01T00:00:00Z"' \
  --project=PROJECT_ID \
  --format=json \
  --limit=100

# Find IAM policy changes
gcloud logging read 'logName:"cloudaudit.googleapis.com/activity"
  AND protoPayload.methodName="SetIamPolicy"' \
  --project=PROJECT_ID \
  --freshness=7d

# Find resource deletions
gcloud logging read 'logName:"cloudaudit.googleapis.com/activity"
  AND protoPayload.methodName=~"delete"
  AND severity>=NOTICE' \
  --project=PROJECT_ID \
  --freshness=7d

# Data access audit log entries
gcloud logging read 'logName:"cloudaudit.googleapis.com/data_access"
  AND protoPayload.serviceName="storage.googleapis.com"
  AND protoPayload.methodName="storage.objects.get"' \
  --project=PROJECT_ID \
  --freshness=24h

# Failed authorization attempts
gcloud logging read 'logName:"cloudaudit.googleapis.com/policy"' \
  --project=PROJECT_ID \
  --freshness=7d
```

## BigQuery Analysis Queries

```sql
-- All destructive operations in the last 30 days
SELECT
  timestamp,
  protopayload_auditlog.authenticationInfo.principalEmail AS principal,
  protopayload_auditlog.methodName AS method,
  protopayload_auditlog.resourceName AS resource,
  resource.labels.project_id AS project,
  protopayload_auditlog.status.code AS status_code,
  protopayload_auditlog.status.message AS status_message
FROM `project.audit_logs.cloudaudit_googleapis_com_activity_*`
WHERE _TABLE_SUFFIX >= FORMAT_DATE('%Y%m%d', DATE_SUB(CURRENT_DATE(), INTERVAL 30 DAY))
  AND protopayload_auditlog.methodName LIKE '%delete%'
ORDER BY timestamp DESC
LIMIT 500;

-- IAM policy changes across the organization
SELECT
  timestamp,
  protopayload_auditlog.authenticationInfo.principalEmail AS changed_by,
  resource.labels.project_id AS project,
  protopayload_auditlog.resourceName AS resource,
  protopayload_auditlog.servicedata_v1_iam.policyDelta.bindingDeltas
FROM `project.audit_logs.cloudaudit_googleapis_com_activity_*`
WHERE _TABLE_SUFFIX >= FORMAT_DATE('%Y%m%d', DATE_SUB(CURRENT_DATE(), INTERVAL 30 DAY))
  AND protopayload_auditlog.methodName = 'SetIamPolicy'
ORDER BY timestamp DESC;

-- Activity per principal (detect anomalous usage)
SELECT
  protopayload_auditlog.authenticationInfo.principalEmail AS principal,
  COUNT(*) AS action_count,
  COUNT(DISTINCT protopayload_auditlog.methodName) AS unique_methods,
  COUNT(DISTINCT protopayload_auditlog.requestMetadata.callerIp) AS unique_ips,
  MIN(timestamp) AS first_activity,
  MAX(timestamp) AS last_activity
FROM `project.audit_logs.cloudaudit_googleapis_com_activity_*`
WHERE _TABLE_SUFFIX >= FORMAT_DATE('%Y%m%d', DATE_SUB(CURRENT_DATE(), INTERVAL 7 DAY))
GROUP BY principal
ORDER BY action_count DESC
LIMIT 50;

-- Service account key creation events (security risk indicator)
SELECT
  timestamp,
  protopayload_auditlog.authenticationInfo.principalEmail AS created_by,
  protopayload_auditlog.resourceName AS service_account,
  protopayload_auditlog.requestMetadata.callerIp AS source_ip
FROM `pro