NeRAM: Next-Generation Rowhammer Attacks and Mitigations

Modern computers have several gigabytes of DRAM memory that is used to store basically all data processed by the computer while it is running. DRAM memory itself consists of cells that store the 1`s and 0`s in capacitors - for example, charged for a 1 and discharged for a 0. Manufacturers are constantly increasing the density of chips and thus decreasing the capacitance of these capacitors in order to optimize storage capacity, performance and efficiency . The result is that parasitic effects can occur, such as the Rowhammer effect. With the Rowhammer effect, high-frequency accesses to two DRAM capacitors ensure that an adjacent capacitor loses so much charge that a stored 1 is read as a 0 the next time it is accessed. This seemingly small problem fundamentally undermines system security, since a single bit can decide whether a program has administrator rights or not. The aim of our research project "NeRAM" is to better understand the Rowhammer effect, to investigate countermeasures and to develop new effective countermeasures. To this end, we investigate the extent of the Rowhammer effect using automated frameworks. An important part is to describe yet unknown properties of the Rowhammer effect, especially those arising in different environments, such as the effects of temperature, EM radiation and aging. In addition, we also examine the Rowhammer effect on devices that have not yet been examined in the context of Rowhammer, namely graphics cards. Graphics cards have special GDDR DRAM memory, which we expect to be vulnerable to Rowhammer-based attacks. On this basis, we will finally propose countermeasures against Rowhammer that specifically protect data from the operating system. We will then use prototypes to demonstrate the effectiveness of the countermeasures. NeRAM is a research collaboration between Florian Adamsky (University of Applied Sciences Hof) and Daniel Gruss (Graz University of Technology).