Four Threat Clusters Using CastleLoader as GrayBravo Expands Its Malware Service Infrastructure

Four distinct threat activity clusters have been observed leveraging a malware loader known as CastleLoader, strengthening the previous assessment that the tool is offered to other threat actors under a malware-as-a-service (MaaS) model.
The threat actor behind CastleLoader has been assigned the name GrayBravo by Recorded Future’s Insikt Group, which was previously tracking it as TAG-150.