Targeting Physically Addressable Memory

摘要

This paper introduces new advances in gaining unauthorised access to a computer by accessing its physical memory via various means. We will show a unified approach for using IEEE1394, also known as firewire, file descriptors and other methods to read from and write into a victim's memory. Thereafter we will show the power of this ability in several example attacks: stealing private SSH keys, and injecting arbitrary code in order to obtain interactive access with administrator privileges on the victim's computer. These advances are based on data structures that are required by the CPU to provide virtual address spaces for each process running on the system. These data structures are searched and parsed in order to reassemble pages scattered in physical memory, thus being able to read and write in each processes virtual address space.The attacks introduced in this paper are adaptable to all kinds of operating system and hardware combinations. As a sample target, we have chosen Linux on an IA-32 system with the kernel-options CONFIG_NOHIGH MEM or C0NFIG_HIGHMEM4G, C0NFIG_VMSPLIT_3G and CONFIG_PAGE_OFFSET= 0xC0000000.