CosmicStrand UEFI implant
CosmicStrand is a rootkit developed by an advanced persistent threat (APT) actor that stays on the victim’s machine even if the operating system is rebooted or Windows is reinstalled – making it very dangerous in the long run. It was used mainly to attack private individuals.
The UEFI firmware is a critical component in the vast majority of hardware. If it is somehow modified to contain malicious code, its activity can be potentially invisible to security solutions and to the operating system’s defenses. Regardless of how many times the operating system is reinstalled, the malware will stay on the device.