He is publicizing the flaw today as the 90-day window he gave Apple has lasped. As of that release, however, the loophole remains unaddressed and Cavallarin says Apple has stopped responding to his emails. app extensions, hide full path from titlebar) makes this tecnique very effective and hard to spot.Ĭavallarin says that he informed Apple of this flaw on February 22nd, and that the company was supposed to address it with the release of macOS 10.14.5 last week. Now the victim is in a location controlled by the attacker but trusted by Gatekeeper, so any attacker-controlled executable can be run without any warning. The victim downloads the malicious archive, extracts it and follows the symlink. To better understand how this exploit works, let’s consider the following scenario:Īn attacker crafts a zip file containing a symbolic link to an automount endpoint she/he controls (ex Documents -> /net//Documents) and sends it to the victim. The second legit feature is that zip archives can contain symbolic links pointing to an arbitrary location (including automount enpoints) and that the software on MacOS that is responsable to decompress zip files do not perform any check on the symlinks before creatig them. The first legit feature is automount (aka autofs) that allows a user to automatically mount a network share just by accessing a “special” path, in this case, any path beginning with “/net/”.įor example ‘ls /net//sharedfolder/’ will make the os read the content of the ‘sharedfolder’ on the remote host () using NFS. And a big part of those experiences is ensuring that the apps we offer are held. But the App Store is more than just a storefront it’s an innovative destination focused on bringing you amazing experiences. He goes on to explain the user can “easily” be tricked into mounting network share drive, and that anything in that folder can then pass Gatekeeper. For over a decade, the App Store has proved to be a safe and trusted place to discover and download apps. In its current implementation, Gatekeeper considers both external drives and network shares as “safe locations.” This means that it allows any application contained in those locations to run without checking the code again. If the code has not been signed, the app won’t open without the user giving direct permission.Ĭavallarin writes on his blog, however, that Gatekeeper’s functionality can be completely bypassed. When a user downloads an app from outside of the Mac App Store, Gatekeeper is used to check that the code has been signed by Apple. This prevents applications from being run without user consent. Gatekeeper is a macOS security tool that verifies applications immediately after they are downloaded. The bypass remains unaddressed by Apple as of last week’s macOS 10.14.5 release. With iOS 17. In case the resource is not available (network down or else) without it something in the OS may get stuck trying to connect to the resource.Security researcher Filippo Cavallarin has publicized what he says is a way to bypass the Gatekeeper security functionality of macOS. I added this entry in /etc/auto_master (you need root access): # Network SharesĪnd then I created /etc/auto_smb: /./Volumes/Storage -fstype=smbfs,soft,noowners,noatime,nosuid is the user allowed to read/write in my NAS and "password" is the password.Īlso please note that the "soft" option is quite important. Click on the box to hide it (should avoid to open a Finder window at each login).Drag&Drop the SMB share icon from desktop.That mounts the SMB share and shows it in the desktop Select your SMB share (I type "smb://NAS326/Storage" where NAS326 isĪn alias to the NAS IP address and Storage is the shared folder).
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