Black Hat 2026 demonstrated attack method using swizzle mode of AMD memory controllers to bypass memory isolation and read or write arbitrary data from memory, including areas with CPU microcode and memory allocated to the PSP (Platform Security Processor). The method allows you to bypass the built-in memory encryption mechanisms (AMD SME/SEV), break the isolation of virtual machines and rewrite the processor microcode. Manipulating the memory controller requires code execution at the kernel level, which reduces the danger of the presented attack technique.
The “swizzle” mode modifies the RAM addressing logic to eliminate sequential access conflicts that arise when reading from different lines in the same memory bank. To eliminate such conflicts in the “swizzle” mode, the controller applies an XOR operation to part of the address bits to separate sequential data blocks into different memory banks. The attack boils down to manipulating the “swizzle” mode on a running system to redistribute physical addresses on the fly.
The attack prototype was demonstrated on AMD 16h family processors used in the PS4 and Xbox One consoles, in which the memory controller addressing configuration registers were documented and there was no mechanism for blocking them after the system boots. In AMD processors of the 17h family and newer (starting with Zen), AMD has implemented a mechanism for blocking access to memory controller configuration registers, and also added protection against substitution of a copy of the microcode flushed into RAM when the processor goes into sleep mode (C6).