Google Workspace Alerts Aggregated By Severity

Type: Alert
Time window: 1h
Match by: severity
Author: Google Cloud Security
Source: github.com/chronicle/detection-rules

Generates alerts based on Google Workspace alerts center and aggregates them based on severity.

Rule body

// Copyright 2023 Google LLC. Licensed under Apache-2.0.

rule google_workspace_alerts_aggregated_by_severity {

  meta:
    author = "Google Cloud Security"
    description = "Generates alerts based on Google Workspace alerts center and aggregates them based on severity."
    rule_id = "mr_311cc4ab-627b-43a1-a744-8d7aa5e44fbf"
    rule_name = "Google Workspace Alerts Aggregated By Severity"
    type = "Alert"
    data_source = "Workspace Alerts"

  events:
    $ws.metadata.vendor_name = "Google Workspace"
    $ws.metadata.product_name = "Google Workspace Alerts"
    $ws.security_result.severity = $severity

  match:
    $severity over 1h

  outcome:
    $risk_score = max(30 +
        if($ws.security_result.severity = "LOW", 10)+
        if($ws.security_result.severity = "MEDIUM", 30)+
        if($ws.security_result.severity = "HIGH", 50)
    )
    $event_count = count_distinct($ws.metadata.id)
    $event_type = array_distinct($ws.metadata.event_type)
    $product_event_type = array_distinct($ws.metadata.product_event_type)
    $security_category_details = array_distinct($ws.security_result.category_details)
    $security_category = array_distinct($ws.security_result.category)
    $security_investigation_tool_link = array_distinct($ws.security_result.detection_fields["security_investigation_tool_link"])
    $security_summary = array_distinct($ws.security_result.summary)
    $alert_severity = array_distinct($ws.security_result.severity)

  condition:
    $ws
}

YARA-L rule structure

Condition

Fires when at least one $ws event in the 1h window.

Events

`$ws`

No field filters (binds the event for correlation only).

Match and correlation

Match key: $severity (security_result.severity)
Within: 1h

Outcome

Outcome variables add context to a detection. When the rule generates an alert, $risk_score is displayed with it.

Field	Expression
`risk_score`	`max(30 + if($ws.security_result.severity = "LOW", 10)+ if($ws.security_result.severity = "MEDIUM", 30)+ if($ws.security_result.severity = "HIGH", 50) )`
`event_count`	`count_distinct($ws.metadata.id)`
`event_type`	`array_distinct($ws.metadata.event_type)`
`product_event_type`	`array_distinct($ws.metadata.product_event_type)`
`security_category_details`	`array_distinct($ws.security_result.category_details)`
`security_category`	`array_distinct($ws.security_result.category)`
`security_investigation_tool_link`	`array_distinct($ws.security_result.detection_fields["security_investigation_tool_link"])`
`security_summary`	`array_distinct($ws.security_result.summary)`
`alert_severity`	`array_distinct($ws.security_result.severity)`