The high-tech industry is once again in a tizzy about the flaws discovered in Intel’s CPUs. Four vulnerabilities in microarchitecture data sampling (MDS) came to light on Tuesday.

MDS is a subclass of previously disclosed vulnerabilities that show filtered data from small structures within the CPU using a locally run speculative execution side channel.

The four newly identified flaws:

Zombieload, or RIDL – Microarchitecture Filling Buffer Data Sampling (MFBDS) – CVE-2018-12130 – Allows authenticated users to use store buffers as an attack vector;
Fallout – Sampling Microarchitecture Buffer Storage Data (MSBDS) – CVE-2018-12126 – Allows authenticated users to use storage buffers as an attack vector;
Microarchitectural Load Port Data Sampling (MLPDS) – CVE-2018-12127 – Allows authenticated users to use the load ports as an attack vector; Y
Microarchitecture Data Sampling Removable Memory (MDSUM) – CVE-2018-11091 – Allows authenticated users to take advantage of non-storable memory as an attack vector.

Zombieload, Fallout and CVE-2018-12127 have a base score of 6.5, based on the industry standard Common Vulnerability Storing System (CVSS), which is an average score; CVE-2018-11091 has a base score of 3.8, which is low.

The practical exploitation of MDS failures is a very complex task, according to Intel, and MDS alone does not provide an attacker with a way to point to specific data that is leaking.

However, “if you get enough random data, you could perform an AI analysis and solve it,” suggested Rob Enderle, principal analyst of the Enderle Group.

“The regulations do not say it’s okay if there’s a violation and the stolen data is random,” he told TechNewsWorld.

Attacks could be initiated by using malicious JavaScript in a web page (a fairly common attack technique) or from a virtual machine located in the cloud.

However, consumers should not worry, according to Kevin Krewell, principal analyst at Tirias Research.

“From what I’ve read, MDS is a complex set of attacks, and it’s not something that would be used to point to a typical consumer PC,” he told TechNewsWorld. “The MDS attack is an attack on the virtual machine architectures (hypervisor) more associated with servers, not with the client PC.”

Intel said it was not aware of any vulnerabilities reported in the real world of the four vulnerabilities so far.
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About the speculative execution

Speculative execution is a technique used by most modern high performance processors to improve performance by executing instructions before they know they are needed. Think of it as a good assistant who anticipates your instructions and carries them out in advance.

Speculative execution reduces latency and draws greater parallelism. Their results can be discarded if subsequent instructions are not necessary, although the predictions are generally correct, according to Intel.

Speculative operations do not affect the architectural status of the processor, but may affect the state of the microarchitecture, including the information stored in the buffers and lookaside translation caches.

Lateral channel methods work by measuring the microarchitecture properties of a system. Side channels have no direct influence on the execution of a program and do not allow data modification or deletion.
Available arrangements

Intel and other affected high-tech companies (operating system vendors, virtual machine monitor (VMM) vendors and other software developers) have issued patches for MDS failures.

The Intel microcode is available on GitHub.

Microsoft has released software updates to help mitigate vulnerabilities. Apple has released a security patch for macOS Mojave. The Amazon AWS cloud service has been patched and Google has patched Chromebooks.

Intel recommends that end users and system administrators check with the manufacturers of their systems and system software vendors, and apply the available updates as soon as possible.

The Intel application, operating system, and hypervisor software updates should have minimal impact on most PC client applications, Intel said, but performance or resource utilization may be affected in some of the workloads of the PC. data center.

Intel recommends customers who have applied the updates but can not guarantee that their systems are running reliable software and that they use multiple threads simultaneously. They should also obtain guidance from their operating system and VMM software vendors, as well as consider the security threat model for their particular environment.

Intel has not recommended disabling Intel HT (hyper-threading) because that single step would not provide protection against MDS.

MDS is addressed in hardware, beginning with certain Intel Core 8th and 9th generation processors and the Intel Xeon family of processors. Future Intel processors will include hardware mitigations to address these vulnerabilities.
Fallout of defects

“All modern high-performance processors use speculative execution,” said Krewell of Tirias, “but not all speculative execution designs are the same – for example, AMD has not seen as many problems as Intel has, and to date, AMD believes it, it’s not affected by MDS. ”

Intel CPUs have been hit by speculative execution vulnerabilities before. Three vulnerabilities discovered last summer affected the technology of Intel’s software protection extensions (SGX), its operating system and system management mode (SMM) and its hypervisor software. Those defects had high severity ratings.

Apparently, speculative execution opens the door to difficult vulnerabilities that can not be fixed in an absolute way but can be mitigated. It’s like incurring permanent damage to a broken leg and having to use a crutch for the rest of your life.

The benefits of speculative execution, at least the benefits of Intel’s implementation, have been questioned.

“Speculative execution allows CPUs to perform better, but these vulnerabilities are paralyzing processors and reducing their performance,” Enderle observed.

The patches can create other problems, he said. “Having to install them is like buying a 250 hp car and reducing engine output to 175 hp because there are problems, at some point, customers will ask for their money back because they do not get what they paid.”

Intel’s problems are “a great blessing for AMD,” said Enderle. “We were talking to Dell and other AMD customers, and they will start using more AMD CPU.”