A hardware attack targets physical components or low-level platform behavior instead of application code. The target may be a CPU, memory controller, firmware, bus, storage device, or security chip. Attackers may use side channels, fault injection, DMA abuse, malicious peripherals, or direct physical probing to influence or observe the system below the operating system.
This matters because hardware attacks can bypass software assumptions about isolation and trust. A flaw in memory mapping, device access control, or firmware state can expose secrets or let an attacker change behavior without touching an application. Defenses include secure boot, firmware updates, memory protection features, IOMMU use, device whitelisting, tamper resistance, and careful inventory of older platforms whose low-level protections may no longer be reliable.