Google Cloud Platform (GCP) SQL Runner Privilege Escalation to Big Query in Looker

Tenable Research has identified and responsibly disclosed a privilege escalation vulnerability in Looker. The flaw allowed an attacker with control over a Looker instance to abuse the trusted Looker service agent to execute unauthorized BigQuery jobs.

The vulnerability resides in Looker's SQL Runner feature, which is designed to execute SQL queries on a connected database. It was discovered that when running a query on a BigQuery resource, Looker's service agent (roles/looker.serviceAgent) is used. This service agent is configured with a wide range of permissions, including bigquery.jobs.create, bigquery.tables.create, and bigquery.tables.delete, enabling it to perform any BigQuery operation.

An attacker with access to the Looker instance's SQL Runner could exploit this by crafting and executing malicious SQL queries. This allowed them to bypass their own limited permissions and escalate privileges to those of the service agent, granting them full control over the connected BigQuery environment. This could lead to the creation, exfiltration, or deletion of sensitive data within the same project.