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.
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.
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.
Unusual ESXi processes (vmx, hostd) reading datastore files and generating outbound HTTPS traffic toward external cloud storage endpoints. Defender perspective: anomalous datastore activity followed by network transfers to Dropbox, AWS S3, or other storage services.