UNC6148 Backdoors Fully-Patched SonicWall SMA 100 Series Devices with OVERSTEP Rootkit

A threat activity cluster has been observed targeting fully-patched end-of-life SonicWall Secure Mobile Access (SMA) 100 series appliances as part of a campaign designed to drop a backdoor called OVERSTEP. The malicious activity, dating back to at least October 2024, has been attributed by the Google Threat Intelligence Group (GTIG) to a group it tracks as UNC6148. The tech giant assessed with