Subj : A new ZenHammer attack is targeting more AMD CPUs
To   : All
From : TechnologyDaily
Date : Tue Mar 26 2024 18:45:05

A new ZenHammer attack is targeting more AMD CPUs

Date:
Tue, 26 Mar 2024 18:31:12 +0000

Description:
Researchers pull off the RowHammer attack on AMD Zen architecture.

FULL STORY
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The infamous Rowhammer DRAM attack can now be pulled off on some AMD CPUs as 
well, academic researchers from ETH Zurich have proved. 

As reported by BleepingComputer , the researchers dubbed the attack 
ZenHammer, after cracking the complex, non-linear DRAM addressing functions 
in AMD platforms. 

For the uninitiated, the Rowhammer DRAM attack revolves around changing data 
in Dynamic Random Access-Memory (DRAM), by repeatedly hammering, or 
accessing, specific rows of memory cells. Memory cells keep information as 
electric charges. These charges determine the value of the bits, which can 
either be a 0, or a 1. As the density of the memory cells in todays chips is 
fairly big, hammering can alter the state in adjacent rows, or flip the 
bit.By flipping specific bits, the attackers can pull cryptographic keys, or 
other sensitive data , BleepingComputer explained. Purely theoretical? 

This means that AMD has joined Intel and ARM CPUs who were already known to 
be vulnerable to hammering attacks. 

The researchers tested their theory on different platforms. For AMD Zen 2, 
they were successful 70% of the time. For AMD Zen 3, 60%. For AMD Zen 4, 
however, they were only successful 10% of the time, suggesting that the 
changes in DDR5 such as improved Rowhammer mitigations, on-die error 
correction code (ECC), and a higher refresh rate (32 ms) make it harder to 
trigger bit flips." 

While usually academic research is purely theoretical, the researchers said 
this attack could be pulled off in the real world, too. They simulated 
successful attacks targeting the systems security, and manipulating page 
table entries for unauthorized memory access. 

Those fearing ZenHammer, its important to stress that these types of attacks 
are quite difficult to pull off. Whats more, there are patches and 
mitigations. Earlier this week, AMD released a security advisory with 
mitigation options. More from TechRadar Pro Your DDR4 memory could be facing 
the return of some serious assaults Here's a list of the best firewalls 
around today These are the best endpoint security tools right now



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Link to news story:
https://www.techradar.com/pro/security/a-new-zenhammer-attack-is-targeting-mor
e-amd-cpus


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