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.[1]
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.[2]
Incidents have been observed where adversaries have created backups of cloud instances and transferred them to separate accounts.[3]
| ID | Name | Description |
|---|---|---|
| G1032 | INC Ransom |
INC Ransom has used Megasync to exfiltrate data to the cloud.[4] |
| G1039 | RedCurl |
RedCurl has used cloud storage to exfiltrate data, in particular the megatools utilities were used to exfiltrate data to Mega, a file storage service.[5][6] |
| ID | Mitigation | Description |
|---|---|---|
| M1057 | Data Loss Prevention |
Data loss prevention can prevent and block sensitive data from being shared with individuals outside an organization.[7] [8] |
| M1037 | Filter Network Traffic |
Implement network-based filtering restrictions to prohibit data transfers to untrusted VPCs. |
| M1054 | Software Configuration |
Configure appropriate data sharing restrictions in cloud services. For example, external sharing in Microsoft SharePoint and Google Drive can be turned off altogether, blocked for certain domains, or restricted to certain users.[9] [10] |
| M1018 | User Account Management |
Limit user account and IAM policies to the least privileges required. |
| ID | Data Source | Data Component | Detects |
|---|---|---|---|
| DS0015 | Application Log | Application Log Content |
Monitor logs for SaaS applications to detect instances of data being shared inappropriately. For example, in Microsoft 365, file sharing events will appear in Audit logs under the event names |
| DS0010 | Cloud Storage | Cloud Storage Creation |
Monitor account activity for attempts to create and share data, such as snapshots or backups, with untrusted or unusual accounts. |
| Cloud Storage Metadata |
Periodically baseline cloud storage infrastructure to identify malicious modifications or additions. |
||
| Cloud Storage Modification |
Monitor for anomalous file transfer activity between accounts and/or to untrusted/unexpected VPCs. |
||
| DS0029 | Network Traffic | Network Traffic Content |
Monitor network traffic content for evidence of data exfiltration, such as gratuitous or anomalous internal traffic containing collected data. Consider correlation with process monitoring and command lines associated with collection and exfiltration. |
| DS0020 | Snapshot | Snapshot Creation |
Monitor account activity for attempts to create and share data, such as snapshots or backups, with untrusted or unusual accounts. |
| Snapshot Metadata |
Periodically baseline snapshots to identify malicious modifications or additions. |
||
| Snapshot Modification |
Monitor account activity for attempts to share data, snapshots, or backups with untrusted or unusual accounts on the same cloud service provider. Monitor for anomalous file transfer activity between accounts and to untrusted VPCs. |