Researchers have developed a new fuzzing -based technique called " Blacksmith " that revives Rowhammer vulnerability attacks against modern DRAM devices, bypassing existing protection measures.
See also: Rowhammer attacks: They even “hit” modern RAM!
The emergence of this new Blacksmith method demonstrates that today's DDR4 modules are vulnerable to exploitation, allowing a variety of attacks to be carried out.
Rowhammer is a security exploit that relies on the leakage of electrical charges between adjacent memory cells, allowing a malicious actor to flip 1s and 0s and change the contents in memory.
This powerful attack can bypass all software-based security mechanisms, leading to privilege escalation, memory corruption, and more.
It was first discovered in 2014 and within a year, two privilege escalation exploits were already available.
Gradually, this became a widespread problem and even Android tools were developed that exploited the Rowhammer vulnerability in smartphones to gain root access.
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The mitigations implemented to address this problem first appeared insufficient in March 2020, when academic researchers demonstrated that it was possible to circumvent them.
Manufacturers had implemented a set of mitigations called “Target Row Refresh” (TRR), which was mainly effective in keeping the then-new DDR4 safe from attacks.
The attack used against him was called "TRRespass" and was another fuzzing-based technique that successfully found exploitable Rowhammering patterns.
The newest DDR5 DRAM modules are already available in the market and their adoption will accelerate over the next two years.
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In DDR5, Rowhammer may not be as big of a problem, as TRR is replaced by “refresh management,” a system that monitors activations in a bank and issues selective refreshes once a threshold is reached.
This means that scalable fuzzing on a DDR5 DRAM device would be much more difficult and potentially much less effective, but that remains to be seen.
