AMD constantly releases new drivers throughout the year as games are released, and those are where you’ll find performance bumps. This doesn’t unlock any new Vega features. Some reports written when AMD teased the Adrenalin name suggested this new Radeon Software could supercharge your frame rate. "We have shown this concept of a new class of dangerous attacks, which is particularly relevant in the context of cloud computing, where several customers share the same hardware," Razavi says, "It also raises questions for the future." For instance, he wants to find out if there are other, similar attacks and whether an "Inception"-like attack is also possible on CPUs from other manufacturers.What you won’t find are gargantuan performance updates. That, of course, is a very serious security vulnerability, so Razavi informed AMD in February to make sure they had time to come up with a patch before the research paper was published (AMD assigned the number CVE-2023-20569 to the vulnerability). In this way, the ETH researchers were able to leak data from anywhere in the computer's memory, including sensitive information such as the hash of the root password. Since the CPU was convinced that the entries in the look-up table originated from instructions it had seen before, the security feature that was meant to ensure that only trustworthy predictions are taken into consideration was bypassed. Just like in the movie, the researchers could plant an idea in the CPU while it was-in a sense-dreaming.Īs a consequence, the look-up table-which the CPU continuously creates from past instructions-could, once again, be manipulated. After a lengthy search, they stumbled upon something strange: "It looked as though we could make the CPUs manufactured by AMD believe that they had seen certain instructions before, whereas in reality that had never happened," says Trujillo. Nevertheless, Razavi and his co-workers set out to test whether even with the new security measures an attack could be launched. "The Spectre attack, which was discovered in 2018, is based on such mispredictions," says Razavi, "but initially it seemed that manufacturers had found ways to mitigate it." In fact, chip manufacturers have provided features for partly deleting the look-up table when switching between security contexts (that is, when the sensitive kernel of the computer is accessed) or adding a bit of information that tells the CPU whether or not a prediction in the look-up table was created in the kernel, and can therefore be trusted. Occasionally, however, it makes the wrong guess, and such a misprediction can be exploited by an attacker to gain access to sensitive information. In the vast majority of cases, the CPU is right and thus saves a lot of valuable computing time. This is where guessing comes into play: Based on past experience, the CPU creates a kind of look-up table and uses it to make a guess as to the most likely next step, which it then executes. As a result, the CPU would have to spend a lot of its time waiting for fresh data in order to make a decision. CPUs have become incredibly fast in recent years, but the speed at which data can be transferred from the memory (DRAM) to the CPU has not been able to keep up with that acceleration. At certain points in the execution, the following command may depend on a choice made based on some information that has to be retrieved from the computer's memory. In modern computers, guesses are needed because during the execution of a program-a game, say, or a web browser-the CPU has to make hundreds of millions of decisions per second. "Still," Wikner adds, "the crux of the matter with all these attacks is rather simple-namely, the fact that a computer's CPU has to make guesses all the time, and those guesses can be tampered with." ![]() "In fact, much like the movie of the same name, the Inception attack is particularly complex and difficult to explain," says master's student Daniël Trujillo, who found this new attack during his thesis work in Razavi's group, supervised by Ph.D. While Razavi's research paper contains names that are reminiscent of James Bond and disaster movies-"Spectre" and "Meltdown" make an appearance-the bulk of it is intricate computer science. Razavi and his colleagues present their research at the conference USENIX Security 2023 this week. A team of researchers at ETH Zurich led by Kaveh Razavi, professor in the Department of Information Technology and Engineering, has demonstrated a serious vulnerability of certain CPUs (central processing units) whereby an attacker can plant the equivalent of an idea in a victim's CPU, coax it into executing certain commands, and thus retrieve information. While sharing dreams and planting such ideas is impossible in reality, something very similar has recently been achieved in the world of computers.
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