The Downfall vulnerability, also known as Gather Data Sampling (GDS) by Intel, is one of the latest vulnerabilities identified in Intel processors. It exposes users to possible malicious attacks and the vulnerability affects most 6th to 11th generation Intel processors. This vulnerability is related to the speculative execution of Advanced Vector Extensions (AVX) instructions, which allow the contents of vector registers to be exposed. It is based on the AVX SIMD Gather instruction, which can be used to retrieve data from memory during speculative execution. In other words: It allows confidential information to be read, such as: B. Encryption keys, from memory, even if this should be prohibited.
A complaint filed against Intel alleges that the company knew about the vulnerability since 2018 but did not fix the flaw before publicly disclosing the flaw this year. Affected computer buyers had to install a patch that slowed the performance of their processors by up to 50%. This situation has raised concerns about Intel’s data security and liability.
Many Intel customers are left with faulty processors that are either extremely vulnerable to attack or need to be slowed beyond recognition to repair. Ultimately, these are not the processors that plaintiffs and class members purchased. Their performance is completely different and their value is much lower. And Intel knew for years that this would all happen eventually.
In 2020, Linus Torvalds, the inventor of the Linux kernel, shared his thoughts on Intel’s AVX-512 instruction set on a mailing list. In the comment he left, Torvalds hoped that the AVX-512 would suffer a painful death. For the father of Linux, the AVX-512 instruction set is only beneficial for the HPC market and comes with real disadvantages. In his opinion, Intel should stop wasting resources on new instruction sets and focus on things that really matter.
“I hope the AVX-512 suffers a painful death and Intel starts solving the real problems instead of trying to create magic instructions and then create benchmarks to build on,” he said. He also wanted the chipmaker to focus more on ordinary code that wasn’t HPC (high performance computing) or other unnecessary special cases.
I’ve said it before and I’ll say it again: When x86 reached its peak, Intel dominated the market and outperformed all competitors. However, when it came to floating point (FP) operations, absolutely everyone performed better than Intel. Intel’s FP performance was relatively weak, but outside of the benchmarks that didn’t matter. This situation repeats itself today with the AVX-512. Although important aspects can be found, these are not decisive for the overall sales of the machines.
An underestimated design problem
Plaintiffs seek compensation for Intel’s informed decision to sell processors with demonstrably defective designs without telling the truth, and for an alleged repair that destroys the performance of their processors. A dangerous solution that runs counter to the (quite serious) problem that requires it.
In the 1990s, high-end processors began incorporating a design technique called branch prediction, a speculative technique intended to prevent the processor from freezing while waiting for information from relatively slow system memory. This technique has led to significant increases in computing power and efficiency and spawned other “speculative execution” techniques, including subsystems that allow CPUs to execute instructions out of order and even predict the outcome of future instructions.
For more than a decade, all modern processors have implemented these execution functions. They are now a basic feature of all processors manufactured by Intel and its competitors, and without them the sufficient performance expected from processors cannot be achieved.
Major design flaw: failure to comply with segmentation
Modern processors also apply segmentation, which means that privileged computer programs and the resources they use (i.e. system memory and hardware) must be separated from programs run by users. This is also an essential feature of all modern processors.
However, Intel has poorly designed these critical systems across billions of its CPUs. When Intel processors execute instructions speculatively, they are designed to discard the results of the execution if the processor makes an error. Instead, Intel’s processors leave side effects – data remains in buffers or the processor’s cache even after the results of speculative execution are discarded. Worse, Intel’s processors allow speculatively executed code to see system resources and information that only a privileged operating system or computer program should see, violating segmentation.
This design flaw manifested itself in catastrophic form in January 2018, when it was revealed that Intel’s processors suffered from vulnerabilities called Specter and Meltdown – attack vectors that exploited Intel’s flawed design. These vulnerabilities had devastating consequences, and Intel rushed to fix them, promising fixes in the hardware and firmware of its processors, particularly the then-upcoming 9th generation of processors.
The Specter and Meltdown exploits were not just individual vulnerabilities. They were part of a large category of vulnerabilities that stemmed from Intel’s flawed design. In fact, Specter and Meltdown led to numerous variants shortly after their release:
In the summer of 2018, as Intel was dealing with the aftermath of Specter and Meltdown and promising a hardware fix for future generations of CPUs, Intel received two separate third-party vulnerability reports that pointed to a specific set of instructions for Intel CPUs called Advanced Vector Extensions (“AVX”).
The filing then cites a June 16, 2018, social media post by Alexander Yee, a hardware enthusiast, about a Specter data leak related to AVX, as well as an article by him discussing proof-of-concept exploit -Code for the instruction set goes This has reportedly been delayed until August 7, 2018 at Intel’s request.
I just wrote a blog about a (theoretical) new thing #Spectrum Exploit variant for @Intel Processor involved #AVX And #AVX512 Instructions. Should I piss off the world and just publish it? Or should I do the right thing and give it to Intel first? Severity 6.0 via CVSS 3.0.
— Alexander Yee (@Mysticial) June 16, 2018
Two different researchers told Intel that its AVX instructions, which perform critical CPU functions related to encryption, media, gaming and running memory-optimized computer programs, were vulnerable to the same class of attacks as Specter and Meltdown. Intel acknowledged both reports simultaneously.
But despite promising a hardware overhaul to mitigate speculative execution vulnerabilities right around the time researchers uncovered the vulnerabilities in Intel’s AVX instructions, Intel did nothing. Back then, the chips weren’t patched, and for three consecutive generations, Intel didn’t redesign its chips to ensure that AVX instructions worked safely when the processor executed them speculatively.
Worse, according to the complaint, Intel created secret stamps associated with these instructions that it did not disclose to anyone. These secret buffers, coupled with side effects in the CPU cache, opened something of a backdoor into Intel’s CPUs, allowing an attacker to use AVX instructions to easily retrieve sensitive information from memory – including encryption keys used for the Advanced Encryption Standard (“AES”) encryption – exploiting the very design flaw that Intel supposedly fixed after Specter and Meltdown.
For years, Intel allegedly knowingly sold billions of processors with this massive vulnerability, compromising the foundations of network security, communications and data storage for Intel processors used in PCs, cloud servers and embedded computers used in functional MRIs, power grids and Industrial control systems are used.
On August 24, 2022, a Google engineer who discovered the undisclosed buffers associated with AVX instructions reported to Intel that about ten of its processors were vulnerable to the same type of attacks as those that caused Intel’s Specter and Meltdown AVX instructions, and Intel responded by asking the engineer not to publish the results.
On August 18, 2023, about a year after Intel was informed of the AVX vulnerability, the Google engineer published an academic article and website for the first time disclosing Intel’s secret AVX buffers and the ongoing vulnerability. His CPUs belong to the same category of attacks as Specter and Meltdown, which he called “Downfall”. As already indicated, billions of processors are affected, especially 6th to 11th generation Intel processors.
Since releasing its 9th generation CPUs in October 2018, Intel has told customers that it has developed a hardware fix for the design flaw that caused Specter and Meltdown and that all 9th generation (and later) CPUs will include this have integrated. And Intel had told customers that it had fixed all vulnerabilities in its CPUs – albeit with significant performance hits – to combat Specter and Meltdown. But since 2018, before many of these supposedly patched CPUs were released, Intel knew that its AVX instructions were at risk of the same category of attacks as Specter and Meltdown.
Deliberately hiding vulnerabilities in Intel processors
Intel—which had exclusive knowledge of the relevant instructions, secret buffers, its processor design, and its Specter/Meltdown defenses—told processor and computer buyers nothing, even though it sold billions of knowingly defective processors over a period of years.
The plaintiffs have defective CPUs at their disposal, the performance and functionality of which must be significantly impaired in order to “mitigate” their downfall vulnerability. These are not the central processing units they purchased.
Plaintiffs were angered by Intel’s conscious decision not to tell the truth about its processors, leaving plaintiffs and proposed class members – the people and companies that purchased affected Intel CPUs or integrated processor computers – CPUs and computers stay that are worth much less than what you paid for them. At the same time, these processors and the computers built on them perform far worse than expected under normal use, remain defective, and are seriously vulnerable to a whole class of devastating cyberattacks.
The plaintiff, Darques Smith, lives in San Diego, California. In February 2022, Smith purchased a Dell Alienware laptop equipped with an 11th generation Intel Core i7-11800H processor running on Tiger Lake-H CPU architecture. Smith uses his computer for gaming, programming and coding with Video Studio, and editing videos and photos with Photoshop, among other things.
Because Downfall was caused by a defect that was known to Intel since 2018 but was never disclosed, the plaintiffs are seeking compensation for Intel’s knowing decision to sell processors with obviously defective designs without telling the truth and for a so-called fix that the performance of their processors destroys processors – a harmful cure that competes with the (quite serious) illness that requires it.
Source: Legal complaint
And you ?
What is your opinion on this topic?
How do you think Intel plans to meet its responsibilities to computer buyers affected by this security breach?
What lessons can we learn from this situation for the future of processor design and data security?
See also:
Torvalds: I hope that the AVX-512 goes away and Intel starts solving real problems instead of creating instructions and then creating benchmarks to base them on
Intel releases open source library with C++ header files for AVX-512 QuickSort, 10-17x faster sorts in NumPy
Clear Linux is preparing to compile Qt with AVX-2 instructions. What performance improvement can we expect?
Intel is launching the third-generation Xeon Scalable processor for data centers, codenamed Ice Lake, offering up to 40 cores per socket