Exfiltration to Cloud Storage
Where this stands
2 published detections cover this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
Adversaries may exfiltrate data to a cloud storage service rather than over their primary command and control channel. Cloud storage services allow for the storage, edit, and retrieval of data from a remote cloud storage server over the Internet. Examples of cloud storage services include Dropbox and Google Docs. Exfiltration to these cloud storage services can provide a significant amount of cover to the adversary if hosts within the network are already communicating with the service.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN1571
Unusual processes (e.g., powershell.exe, excel.exe) accessing large local files and subsequently initiating HTTPS POST requests to domains associated with cloud storage services (e.g., dropbox.com, drive.google.com, box.com). Defender perspective: correlation between file reads in sensitive directories and high outbound traffic volume to known storage APIs.
- AN1572
Processes such as curl, wget, rclone, or custom scripts executing uploads to cloud storage endpoints. Defender perspective: detect chained events where tar/gzip is executed to compress files followed by HTTPS PUT/POST requests to known storage services.
- AN1573
Applications or scripts invoking cloud storage APIs (Dropbox sync, iCloud, Google Drive client) in unexpected contexts. Defender perspective: detect sensitive file reads by non-standard applications followed by unusual encrypted uploads to external cloud storage domains.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.