Google Cloud Platform (GCP) Cross-Tenant Denial of Wallet Through Big Query in Looker Studio

Tenable Research has identified and responsibly disclosed a "Denial of Wallet" vulnerability in Looker Studio. This vulnerability allowed an attacker to abuse the Looker Studio Linking API to exhaust a victim's cloud service billing account without their knowledge.

This attack exploited a flaw in the Looker Studio Linking API's handling of billing information. An attacker could craft a malicious URL that, when clicked, would attach a victim's BigQuery billing project ID to an attacker-owned, public report. This report was designed to execute a large number of resource-intensive queries, each of which would run on the victim's billing account.

By creating a report with hundreds or even thousands of charts, each triggering a separate BigQuery job, the attacker could launch a denial-of-wallet attack. When the victim visited the malicious link, the queries would execute in their GCP project, consuming their BigQuery quota and running up significant costs on their bill without their consent or knowledge. The attack could be applied to any cloud data source that bills for resource consumption.

Proof of Concept

Set up a mock data source:

1. Create a BigQuery data set and a table. For example, we will name the dataset “attackerdataset” and the table “attackertable” and make them public. Alternatively, you can choose a public BigQuery dataset and table for this step

Set up the attacker’s report:

1. Create a report.
2. Choose the Big Query connector.
3. Choose the specific data source created in the first step: , “attacker’s-project.attackerdataset.attackertable”
4. Add a chart to the report, preferably a table, by pressing “Add a chart” and choosing a Table. Create hundreds of them, each table is a job that exhausts the billing of the victim when run.
5. Share the report with the victim, and uncheck the “Notify” checkbox
6. Craft the Linking API link and input the report ID of the report you just created, and the project ID of the victim: https://lookerstudio.google.com/reporting/create?c.reportId=<repordID-of-the-attacker-with-bigquery-queries>&ds.*.billingProjectId=victimsproject
7. Visit the attacker’s website as the victim, and the victim’s billing will be exhausted by hundreds of BigQuery jobs