Scientists have published a paper today detailing a new Spectre-class CPU attack that can be carried out via network connections and does not require the attacker to host code on a targeted machine.
But with NetSpectre, an attacker can simply bombard a computer's network ports and achieve the same results.
Although the attack is innovative, NetSpectre also has its downsides (or positive side, depending on what part of the academics/users barricade you are). The biggest is the attack's woefully slow exfiltration speed, which is 15 bits/hour for attacks carried out via a network connection and targeting data stored in the CPU's cache.
Academics achieved higher exfiltration speeds —of up to 60 bits/hour— with a variation of NetSpectre that targeted data processed via a CPU's AVX2 module, specific to Intel CPUs.
Nonetheless, both NetSpectre variations are too slow to be considered valuable for an attacker. This makes NetSpectre just a theoretical threat, and not something that users and companies should be planning for with immediate urgency. But as we've seen in the past with Rowhammer attacks, as academics spend more time probing a topic, exfiltration speeds will also eventually go up, while the technical limitations that prevent such attack from working will slowly go down and dissipate.
Under the hood, this new NetSpectre attack is related to the Spectre v1 vulnerability (CVE-2017-5753) that Google researchers and academics have revealed at the start of the year.
As such, all CPUs previously affected by Spectre v1 are believed to also be affected by NetSpectre, although academics said that existing vendor mitigations should stop NetSpectre, if they've been deployed with our OS and CPU's firmware.
Readers can find out more about this new NetSpectre attack in a research paper published by four academics from the Graz University of Technology in Austria. The research paper is named "NetSpectre: Read Arbitrary Memory over Network."
This is the second Spectre attack variation that academics have revealed in the span of a week. Last week, researchers from the University of California, Riverside (UCR) have published details about another attack named SpectreRSB that carries out its data exfiltration by abusing the CPU's Return Stack Buffer (RSB).
|Variant||Description||CVE||Codename||Affected CPUs||More info|
|Variant 1||Bounds check bypass||CVE-2017-5753||Spectre v1||Intel, AMD, ARM||Website|
|Variant 1.1||Bounds check bypass on stores||CVE-2018-3693||Spectre 1.1||Intel, AMD, ARM||Paper|
|Variant 1.2||Read-only protection bypass||CVE unknown||Spectre 1.2||Intel, AMD, ARM||Paper|
|Variant 2||Branch target injection||CVE-2017-5715||Spectre v2||Intel, AMD, ARM||Website|
|Variant 3||Rogue data cache load||CVE-2017-5754||Meltdown||Intel, ARM||Website|
|Variant 3a||Rogue system register read||CVE-2018-3640||-||Intel, AMD, ARM, IBM||Mitre|
|Variant 4||Speculative store bypass||CVE-2018-3639||SpectreNG||Intel, AMD, ARM, IBM||Microsoft blog post|
|-||Return mispredict||-||SpectreRSB||Intel, AMD, ARM||Paper|
|-||Access-driven remote Evict+Reload cache attack||-||NetSpectre||Intel, AMD, ARM||Paper|