Security Experts:

Apple Adds Spectre Protections to Safari, WebKit

Updates released by Apple on Monday for iOS, macOS and Safari should mitigate the effects of the vulnerabilities exploited by the recently disclosed attack method named Spectre.

Apple informed customers that iOS 11.2.2 and macOS High Sierra 10.13.2 Supplemental Update include security improvements for Safari and WebKit. The Safari improvements are also included in version 11.0.2 of Apple’s web browser.

The latest updates address the Spectre vulnerabilities, specifically CVE-2017-5753 and CVE-2017-5715. Mitigations for the Meltdown attack were rolled out by Apple, before the flaws were disclosed, with the release of iOS 11.2, macOS 10.13.2 and tvOS 11.2. Apple Watch is not vulnerable to either of the attack methods.

Apple’s analysis showed that the Spectre vulnerabilities “are extremely difficult to exploit,” even by a local app running on iOS or macOS, but the company warned that remote exploitation via JavaScript running in the browser is possible.

“Our current testing indicates that the upcoming Safari mitigations will have no measurable impact on the Speedometer and ARES-6 tests and an impact of less than 2.5% on the JetStream benchmark,” Apple said last week.

Apple believes the Meltdown technique, which relies on a vulnerability tracked as CVE-2017-5754, has the most potential for exploitation.

As for the WebKit engine, which is used by Safari, Mail and the App Store, its developers have explained why it's impacted by Spectre and Meltdown.

“To initiate a Spectre- or Meltdown-based attack, the attacker must be able to run code on the victim’s processor. WebKit is affected because in order to render modern web sites, any web JavaScript engine must allow untrusted JavaScript code to run on the user’s processor,” WebKit developers said. “Spectre impacts WebKit directly. Meltdown impacts WebKit because WebKit’s security properties must first be bypassed (via Spectre) before WebKit can be used to mount a Meltdown attack.”

Meltdown and Spectre can be used by malicious actors to bypass memory isolation mechanisms and access passwords, photos, documents, emails, and other sensitive information.

The attacks work against devices with Intel, AMD and ARM processors. Intel has been hit the hardest, while AMD claims the risk of attacks is low and ARM found that only ten of its CPUs are impacted.

Patches and workarounds have already been released by several major vendors, but they can introduce significant performance penalties, and Microsoft’s updates may also break Windows and various apps.

*updated with information about WebKit

Related: Qualcomm Working on Mitigations for Spectre, Meltdown

Related: Lawsuits Filed Against Intel Over CPU Vulnerabilities

Related: Industry Reactions to Meltdown, Spectre Attacks

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.