Adversaries may exfiltrate data by transferring the data, including through sharing/syncing and creating backups of cloud environments, to another cloud account they control on the same service.

A defender who is monitoring for large transfers to outside the cloud environment through normal file transfers or over command and control channels may not be watching for data transfers to another account within the same cloud provider. Such transfers may utilize existing cloud provider APIs and the internal address space of the cloud provider to blend into normal traffic or avoid data transfers over external network interfaces.(Citation: TLDRSec AWS Attacks)

Adversaries may also use cloud-native mechanisms to share victim data with adversary-controlled cloud accounts, such as creating anonymous file sharing links or, in Azure, a shared access signature (SAS) URI.(Citation: Microsoft Azure Storage Shared Access Signature)

Incidents have been observed where adversaries have created backups of cloud instances and transferred them to separate accounts.(Citation: DOJ GRU Indictment Jul 2018) 
Transfer Data to Cloud Account
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1537  external_id: T1537     source_name: AWS EBS Snapshot Sharing  description: Amazon Web Services. (n.d.). Share an Amazon EBS snapshot. Retrieved March 2, 2022.  url: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-modifying-snapshot-permissions.html     source_name: TLDRSec AWS Attacks  description: Clint Gibler and Scott Piper. (2021, January 4). Lesser Known Techniques for Attacking AWS Environments. Retrieved March 4, 2024.  url: https://tldrsec.com/p/blog-lesser-known-aws-attacks     source_name: Azure Shared Access Signature  description: Delegate access with a shared access signature. (2019, December 18). Delegate access with a shared access signature. Retrieved March 2, 2022.  url: https://docs.microsoft.com/en-us/rest/api/storageservices/delegate-access-with-shared-access-signature     source_name: Azure Blob Snapshots  description: Microsoft Azure. (2021, December 29). Blob snapshots. Retrieved March 2, 2022.  url: https://docs.microsoft.com/en-us/azure/storage/blobs/snapshots-overview     source_name: Microsoft Azure Storage Shared Access Signature  description: Microsoft. (2023, June 7). Grant limited access to Azure Storage resources using shared access signatures (SAS). Retrieved March 4, 2024.  url: https://learn.microsoft.com/en-us/azure/storage/common/storage-sas-overview     source_name: DOJ GRU Indictment Jul 2018  description: Mueller, R. (2018, July 13). Indictment - United States of America vs. VIKTOR BORISOVICH NETYKSHO, et al. Retrieved September 13, 2018.  url: https://www.justice.gov/file/1080281/download     