This talk presents the current knowledge on Direct Memory Access attacks aiming to unlock a user logon session. The Input Output Memory Management Unit (IOMMU)[1] functioning and its integration within the main operating systems (Windows, macOS and Linux) is firstly addressed. Then, the existing DMA attacks using an external peripheral on a switched on computer are explained with a particular focus on IOMMU bypassing on macOS until 10.12.4 version. These attacks give an access to a valid logon session even if the computer is locked. This research was performed in order to prepare the upcoming french RAPID project by Synacktiv: DMArvest.
[1] Only Intel VT-d technology will be discussed in this document
[2] https://www.defense.gouv.fr/aid/deposer-vos-projets/subventions/rapid