GCP: Storage Bucket IAM Permissions Modified

Rule ID

PH_RULE_GCP_AUDIT_STORAGEBUCKET_IAM_PERM_MODIFIED

Default Status

Enabled

Description

Google Cloud Platform: IAM Permissions on a storage bucket have been modified.

Severity

MITRE ATT&CK® Tactics

Collection

Collection consists of techniques adversaries may use to gather information and the sources information is collected from that are relevant to following through on the adversary's objectives. Frequently, the next goal after collecting data is to steal (exfiltrate) the data. Common target sources include various drive types, browsers, audio, video, and email. Common collection methods include capturing screenshots and keyboard input.

https://attack.mitre.org/tactics/TA0009

MITRE ATT&CK® Techniques

T1530

Data from Cloud Storage Object

Adversaries may access data objects from improperly secured cloud storage. Many cloud service providers offer solutions for online data storage such as Amazon S3, Azure Storage, and Google Cloud Storage. These solutions differ from other storage solutions (such as SQL or Elasticsearch) in that there is no overarching application. Data from these solutions can be retrieved directly using the cloud provider's APIs.

https://attack.mitre.org/techniques/T1530

Impacts

Network

Data Source

GCP via GOOGLE_Pub_Sub

Detection

Correlation

Remediation Guidance

Make sure it is an authorized change

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

bucket_iam_updated

SubPattern Definitions

SubPattern Name: bucket_iam_updated

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

eventType CONTAIN "GCP_Audit_activity_storage_setIamPermissions"

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

emailId,bucketName,action

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT(*) >= 1

Incident Attribute Mapping

This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.

The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern

 bucketName=bucket_iam_updated.bucketName,
emailId=bucket_iam_updated.emailId,
action=bucket_iam_updated.action

FortiSIEM Rules