Apple fixes three macOS flaws under active attack

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Apple has issued a patch to fix multiple vulnerabilities across its various platforms including iOS, macOS, tvOS, watchOS and Safari, including a macOS Big Sur zero-day vulnerability under active attack.

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The exploited macOS flaw, tracked as CVE-2021-30713, lies in Apple's Transparency, Consent and Control (TCC) framework, which manages user consent for permissions across local apps. Apple, however, declined to share the exploit mechanism or the effects of successful exploitation. The company fixed the bug with improved validation.

Security firm Jamf, however, noted in a post that the bug has been exploited by the malware known as XCSSET, discovered in August 2020 by Trend Micro. The flaw can be exploited to grant malicious apps permissions including full disk access and access to screen recording, meaning hackers can take screenshots of infected machines.

The news comes shortly after Apple's head of software, Craig Federighi, said that macOS suffers from an "unacceptable" level of malware, which he blamed on the diversity in the sources of software. He was delivering testimony during the Epic Games vs Apple trial.

The XCSSET malware had initially targeted developers by infecting Xcode projects as a means of spreading through Github repositories. The malware is unique in the way that it's been written in AppleScript, which allows it to control script-enabled Mac applications.

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The malware initially abused two zero-day exploits when it was first discovered, one to steal Safari browser cookies and another to bypass prompts to install a developer version of Safari on a targeted device. Jamf has confirmed that XCSSET is also abusing the TCC flaw.

Alongside this bug, Apple has patched CVE-2021-30663 and CVE-2021-30665, both lying in the WebKit browser engine in Safari and Apple TV, and both under attack.

The former is described as an integer overflow issue that can lead to remote code execution attacks when processing malicious web content. The latter is described as a memory corruption bug that can also lead to remote code execution attacks.

These three flaws have been patched alongside a handful of vulnerabilities, which are outlined in Apple's latest security update. They include flaws in AMD chips, the login window and the Intel graphics driver, among other areas.

Keumars Afifi-Sabet is a writer and editor that specialises in public sector, cyber security, and cloud computing. He first joined ITPro as a staff writer in April 2018 and eventually became its Features Editor. Although a regular contributor to other tech sites in the past, these days you will find Keumars on LiveScience, where he runs its Technology section.