A critical cloud storage attack technique that exploits a fundamental architectural vulnerability shared across all major cloud service providers.
The technique, dubbed cloud bucket hijacking, allows attackers to silently redirect active data streams, including audit logs, telemetry pipelines, and sensitive objects, to attacker-controlled storage environments with minimal risk of detection.
Discovered by security researchers at Palo Alto Networks’ Unit 42, the exploit targets Google Cloud Platform (GCP), Amazon Web Services (AWS), and Microsoft Azure.
The vulnerability stems from a common design choice: globally unique bucket names. Because no two accounts can simultaneously hold the same bucket name, the identity of a storage destination is tied strictly to its name rather than an immutable account owner, creating a severe global namespace risk.
Cloud Bucket Hijacking Technique
The attack chain begins when an adversary compromises a cloud environment and acquires the permissions necessary to delete a target storage bucket.
Once the original bucket is wiped, the attacker immediately provisions a new bucket utilizing the exact same name within their own external account.
This simple name reclamation triggers a devastating chain reaction. Autonomous data streams such as replication pipelines, logging sinks, or transfer jobs that were previously configured to route data to the original bucket remain completely intact.
These automated processes seamlessly continue operations, delivering sensitive objects and audit events straight to the adversary. A particularly alarming element of bucket hijacking is its inherent stealth.
Because the data stream operates without interruption, the sink or replication configurations appear entirely valid during routine security inspections. Organizations are unlikely to detect the compromise until significant data exfiltration has already taken place.
Unit 42 researchers validated this attack methodology across multiple prominent cloud ecosystems.
- Google Cloud: Researchers simulated hijacking via Cloud Logging sinks, Pub/Sub subscriptions, and Storage Transfer Service jobs, requiring only
storage.buckets.deleteandstorage.objects.deletepermissions rather than granular stream modification rights. - Amazon Web Services (AWS): The technique was successfully replicated using Amazon Data Firehose and S3 bucket replication, automatically routing newly written objects to an externally controlled destination bucket.
- Microsoft Azure: While Azure’s soft-delete policies prevent immediate cross-tenant name reuse, attackers leveraged cross-subscription access to reroute Azure Monitor diagnostic pipelines to rogue storage accounts within the same tenant.
A core finding is that broad storage administrator roles, frequently assigned in enterprise setups, inherently include bucket deletion privileges.
In GCP, for example, the standard Storage Admin role allows attackers to execute this hijacking vector without ever needing explicit permissions like logging.sinks.update to modify the underlying data streams.
While Unit 42 has not yet observed this technique exploited in the wild, the extreme difficulty of post-execution detection makes proactive defense critical.
Security teams must enforce the principle of least privilege by restricting bucket deletion permissions strictly to minimal administrative roles. This includes locking down storage.buckets.delete in GCP, DeleteBucket in AWS, and Microsoft.Storage/storageAccounts/delete in Azure.
Organizations should also deploy firm data perimeter controls, such as VPC Service Controls in Google Cloud and Service Control Policies (SCPs) in AWS, to actively block write operations to buckets outside trusted organizational boundaries.
AWS users are specifically advised to enable account-scoped regional namespaces for Amazon S3 to completely eliminate the risk of cross-account name reclamation.
Furthermore, security teams must implement high-severity monitoring alerts for all bucket-deletion API calls, using Data Security Posture Management (DSPM) tools to prioritize and protect sensitive assets.
This research highlights a crucial lesson for cloud security architecture. A design flaw identified in one cloud ecosystem often provides threat actors with a direct blueprint for exploiting other cloud ecosystems, underscoring the need for unified defense strategies across all multi-cloud environments.
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