Apple has released important security updates under macOS 11.3, in response to a serious gatekeeper vulnerability discovered by security researcher Cedric Owens.
The weakness, found in Apple’s ‘Gatekeeper’ tool which normally blocks unrecognised apps from being installed by default, allows a dangerous file to be rigged so as to not trigger the operating system’s inbuilt safeguards.
Writing in a Medium Post entitled ‘Gatekeeper Bypass: 2021 Edition’, Owens demonstrates a terrifying method by which an attacker can ‘very easily craft a macOS payload that is not checked by Gatekeeper.’
Once launched, no warning prompts prevent the user from installing just about any dangerous application, which can also communicate with external servers without even triggering App Transport Security (ATS).
The simplicity of the hack, which leverages the fact that scripts placed in Contents / macOS / directory are not checked, has been described by Objective-See as ‘massively bad’ and ‘a doozy’ of a blog post.
GateKeeper itself was originally introduced in 2012 as part of an effort to stop the spread of malware in Mac OS X ‘Lion’ v10.7.5, and was followed by enforced application notarisation in 2020 under macOS 10.15 ‘Catalina’, as Apple required software developers to have apps officially cleared for authorised use.
In response to the discovery, Apple have released macOS Big Sur 11.3 update with ‘improved state management’ that prevents the ‘bypass’ of Gatekeeper checks, and are urging macOS users to install the upgrade.
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