Facepalm: Spectre-based flaws continue to pose security challenges in recent Intel and AMD CPUs. A newly developed attack can circumvent the protection “barriers” OEMs implemented to prevent personal data leakage. However, microcode and system updates should be available for affected systems.
Six years ago, security researchers unveiled two new vulnerability categories impacting process execution and data protection on CPUs. Meltdown and Spectre made a significant impact in both generalist and tech-focused media, with the latter still troubling CPU manufacturers with new “Spectre-class” flaws discovered periodically.
Two researchers at ETH Zurich in Switzerland have exposed a novel attack capable of “breaking” the barriers set by Intel and AMD against Spectre-like flaws. This new study examines the indirect branch predictor barrier (IBPB), a protection introduced by manufacturers to shield newer CPUs against Spectre v2 (CVE-2017-5715) and similar hardware vulnerabilities.
The researchers initially identified a bug in the microcode for 12th-, 13th-, and 14th-gen Intel Core processors and 5th- and 6th-gen Xeon processors, which malicious actors could exploit to invalidate IBPB protection. Spectre flaws leak “secret” data filtered through branch prediction—a speculative execution method used on modern processors to optimize computing processes, offering notable performance benefits.
Unfortunately, an attacker might theoretically bypass IBPB and attempt to exploit Spectre to uncover root passwords or other sensitive information. Additionally, AMD Zen and Zen 2 processors have incorrect implementations of IBPB protection, enabling someone to craft a Spectre exploit that leaks arbitrary privileged memory contents, such as root password hashes. Zen 3 processors could also be susceptible, although they only discovered a “faint” signal that wasn’t clearly exploitable.
The researchers concentrated on Spectre exploits targeting Linux operating systems, as acquiring Windows or other OS source code is not feasible. The security team shared details of the security issues with AMD and Intel in June 2024, though both companies had already identified the flaws by then. Chipzilla released a patched microcode in March 2024 (INTEL-SA-00982), and the researchers now advise PC users to keep their Intel-based systems updated.
Owners of Zen + and Zen 2 systems should also ensure they have the latest updates for the Linux kernel. The company published a security bulletin regarding the IBPB flaw in 2022. The researchers are actively working with Linux maintainers to integrate their proposed software patch.
