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Netskope Threat Research Labs has observed ongoing targeted attacks in enterprise cloud environments that lead to a malware fan-out effect through automated syncing and sharing of files in the cloud. While monitoring this attack, we captured several instances where the synced filenames were similar to the email addresses of the attack victims. These attachments are often automatically synced to cloud storage applications using file collaboration settings in popular SaaS applications like Office365, Google mail etc. This auto-syncing feature can also be achieved through third party applications as well. Since the filenames appear less suspicious, they are more likely to be viewed as coming from within the organization (and therefore trusted) and shared with others in the same user group.
Figure 1 illustrates this effect in a cloud environment and how Netskope detects the attack patterns at various stages.
Figure 1: Infection propagation in the Cloud
The synced files were all zipped and contained obfuscate