Cloud-based storage services are provided for storing and/or sharing content across multiple devices, where the content is periodically synchronized between the devices and the storage service. Embodiments are directed to detection of bulk operations associated with content stored at a storage service to protect users both proactively and remedially from accidental and/or nefarious content alterations propagating to the storage service and/or other devices. A model based on a usage pattern monitored and provided by a client device may be received at the client device from the storage service. An attempted operation performed on the content may be detected, and the attempted operation may be compared to the model to determine whether the operation deviates from the usage pattern. If the attempted operation deviates from the usage pattern, execution of the attempted operation and synchronization of the content with the storage service may be prevented until the attempted operation is approved.