At the Black Hat 2026 conference, an attack method was demonstrated that utilizes the swizzle mode of AMD memory controllers to bypass memory isolation and read or write arbitrary data from memory, including areas containing CPU microcode and memory allocated to the Platform Security Processor (PSP). This method allows for bypassing built-in memory encryption mechanisms (AMD SME/SEV), breaching virtual machine isolation, and overwriting processor microcode. Manipulating the memory controller requires kernel-level code execution, mitigating the threat posed by the presented attack technique.
Swizzle mode modifies the RAM addressing logic to eliminate conflicts that arise during sequential access, which can occur when reading from different rows in the same memory bank. To avoid such conflicts in swizzle mode, the controller applies an XOR operation to some address bits to separate consecutive data blocks into different memory banks. The attack consists of manipulating swizzle mode on a running system to redistribute physical addresses on the fly.
A prototype attack was demonstrated on AMD 16h-series processors used in the PS4 and Xbox One consoles, which had documented memory controller address configuration registers and lacked a mechanism for locking them after system boot. In AMD 17h-series processors and later (starting with Zen), AMD implemented a mechanism for locking access to the memory controller configuration registers and also added protection against spoofing the microcode copy written to RAM during the processor's sleep mode (C6).
Source: opennet.ru
