GrayBravo’s CastleLoader Activity Clusters Target Multiple Industries www.recordedfuture.com/research/…
Insikt Group continues to monitor GrayBravo (formerly tracked as TAG-150), a technically sophisticated and rapidly evolving threat actor first identified in September 2025. GrayBravo demonstrates strong adaptability, responsiveness to public exposure, and operates a large-scale, multi-layered infrastructure. Recent analysis of GrayBravo’s ecosystem uncovered four distinct activity clusters leveraging the group’s CastleLoader malware, each defined by unique tactics, techniques, and victim profiles. These findings reinforce the assessment that GrayBravo operates a malware-as-a-service (MaaS) model.
For example, one cluster, tracked as TAG-160, impersonates global logistics firms, using phishing lures and the ClickFix technique to distribute CastleLoader while spoofing legitimate emails and exploiting freight-matching platforms to target victims. Another cluster, tracked as TAG-161, impersonates Booking.com, also employing ClickFix to deliver CastleLoader and Matanbuchus and novel phishing email management tools. Further investigation through historical panel analysis linked the online persona “Sparja”, a user active on Exploit Forums, to potential GrayBravo-associated activities, based on the alias’s distinctiveness and related discussion topics.
