According to an Italian security researcher named Filippo Cavallarin, macOS Mojave 10.14.5 and younger are vulnerable to an arbitrary code execution error that Apple refuses to consider. This vulnerability allows a hacker to bypass Gatekeeper, which is the macOS built-in defense tool, and perform whatever he wants without worrying about certificate validation or any other validation. Cavallarin has discovered that it is possible to abuse the macOS automount functionality, which treats external disks and network as secure sites and is associated with a symlink to run any code
without hitting the Gatekeeper.
To prove vulnerability, the researcher created one zip a file containing a symbolic link that automatically shows the endpoints it controls. This file can be sent to the victim and uploaded to the target system. The symlink takes the victim to a location controlled by the attacker and has never been checked by Gatekeeper and that means the hacker will be able to do whatever he wants, including the execution of malicious code. The following short video shows exactly how the scenario could actually unfold.
- An Italian researcher exhibits a security vulnerability that allows hackers to bypass the Gatekeeper.
- The researcher publicly published the PoC code and a video, but Apple has not yet released a solution.
- Apple engineers have included a relative solution in the previous patch, but it was probably not effective enough.
While the concept of "concept code" is quite simple and made available Apple from 22 February 2019, the company failed to correct the issue, although it initially accepted the report as valid. At 15 May 2019, Apple began to completely ignore the investigator's messages that warned them of the next release deadline, so how exactly did we end up here. As there is no solution to this vulnerability, the only solution for macOS users who worry about their security is to disable automount on their system. To do this, the researcher reported the following three steps:
- Edit / etc / auto_master as root
- Note the line beginning with '/ net'
While the method of exploiting this vulnerability seems legitimate, there is some confusion arising from the 10.14.4 release notes. In the DesktopServices section, there is CVE-2019-8589 that promises improved controls that prevent malicious applications from bypassing Gatekeeper's controls. Are these improvements insufficient to mitigate the problem described by the Italian researcher or did not check the correction and falsely claim to reveal a defect? Given that he used the macOS X version 10.14.5 at the beginning of his report, I suspect he is not lying just that Apple engineers believed they corrected the vulnerability but did not.