"Rowhammer works by repeatedly reading data from specific rows of DRAM. This process causes voltage fluctuations in the nearby rows, which can lead those cells to undergo a bit flip. These disturbance errors break the memory protection model that modern computing relies on to ensure data accuracy, program sandboxing, and privilege separation between processes."
It’s so serious because it can be used to dismantle the various protections that keep data secure and processes isolated from each other, and it launches that attack in hardware, far below the detection capabilities of any conventional antivirus or security software.
Long story short - "THEY" can get access to your computer through DDR3 & DDR4. On the other hand "THEY" probably aren't going after you. At least not right now.
Once thought safe, DDR4 memory shown to be vulnerable to “Rowhammer”
To assess the accuracy of the claims, Third I/O employees tested 12 varieties of DDR4 chips, and it didn't take long for eight of them to succumb to bitflipping. The first DIMM to fall was Crucial Ballistix Sport model manufactured by Micron. Ultimately, the researchers also carried out successful Rowhammer attacks against other Crucial- and Micron-branded DDR4 modules, as well as DIMMs from Geil. Interestingly, DIMMs from G.Skill were able to withstand the tests.
Luckily, I bought G.SKILL Ripjaws DDR4 for my new computer.