MacOS Zero-Day Let Attackers Bypass Privacy Preferences

Apple today released patches for zero-day flaws in macOS and tvOS after reports indicated they are under attack. Researchers report attackers have used the macOS vulnerabilities to capture screenshots on a victim's desktop without needing permissions.

CVE-2021-30713, now fixed in the latest macOS 11.4 release, allows an attacker to bypass the Transparency Consent and Control (TCC) framework. This framework controls which resources applications can access. For example, it will give video collaboration software access to the webcam and microphone so people can join video meetings.

Jamf researchers who noticed an uptick of XCSSET malware in the wild began to analyze the threat and discovered it used an exploit for this vulnerability that would allow attackers to gain full disk access, screen recording, or other permissions without requiring the user's consent. When installed on a target device, XCSSET specifically used this bypass to take screenshots.

XCCSSET malware was first reported by Trend Micro last summer. This malware, which targeted Mac developers, infected Xcode projects so they could further spread malware via Github repositories. When it was first discovered, XCSSET used two zero-day exploits – one to steal Safari browser cookies and another to install a developer version of the Safari application. Jamf's analysis led to the discovery of this third vulnerability used to bypass the TCC framework.

The two tvOS vulnerabilities under attack include CVE-2021-30665 and CVE-2021-30663, both of which affect WebKit. Patches are available for Apple TV 4K and Apple TV HD. Processing maliciously crafted Web content may lead to arbitrary code execution on a vulnerable machine.

In addition to fixes for the three zero-days, Apple released a range of security patches to address issues across multiple products. The Department of Homeland Security's Cybersecurity and Infrastructure Security Agency (CISA) issued an alert on the fixes.

Read the full Jamf blog post for more details on CVE-2021-30713.