Foreshadow

Foreshadow, known as L1 Terminal Fault (L1TF) by Intel, is a vulnerability that affects modern microprocessors that was first discovered by two independent teams of researchers in January 2018, but was first disclosed to the public on 14 August 2018. The vulnerability is a speculative execution attack on Intel processors that may result in the disclosure of sensitive information stored in personal computers and third-party clouds. There are two versions: the first version (original/Foreshadow) (CVE-2018-3615) targets data from SGX enclaves; and the second version (next-generation/Foreshadow-NG) (CVE-2018-3620 and CVE-2018-3646) targets virtual machines (VMs), hypervisors (VMM), operating systems (OS) kernel memory, and System Management Mode (SMM) memory. A listing of affected Intel hardware has been posted.

Foreshadow is similar to the Spectre security vulnerabilities discovered earlier to affect Intel and AMD chips, and the Meltdown vulnerability that also affected Intel. AMD products are not affected by the Foreshadow security flaws. According to one expert, "[Foreshadow] lets malicious software break into secure areas that even the Spectre and Meltdown flaws couldn't crack". Nonetheless, one of the variants of Foreshadow goes beyond Intel chips with SGX technology, and affects "all [Intel] Core processors built over the last seven years".

Foreshadow may be very difficult to exploit. As of 15 August 2018, there seems to be no evidence of any serious hacking involving the Foreshadow vulnerabilities. Nevertheless, applying software patches may help alleviate some concern, although the balance between security and performance may be a worthy consideration. Companies performing cloud computing may see a significant decrease in their overall computing power; people should not likely see any performance impact, according to researchers. The real fix, according to Intel, is by replacing today's processors. Intel further states, "These changes begin with our next-generation Intel Xeon Scalable processors (code-named Cascade Lake), as well as new client processors expected to launch later this year [2018]."

On 16 August 2018, researchers presented technical details of the Foreshadow security vulnerabilities in a seminar, and publication, entitled "Foreshadow: Extracting the Keys to the Intel SGX Kingdom with Transient Out-of-Order Execution" at a USENIX security conference.