Talal Haj Bakry and Tommy Mysk (Mastodon):

Until macOS 26.4, Archive Utility had nearly unrestricted filesystem access. Combined with a drag-and-drop sandbox quirk, this let an attacker bypass App Sandbox data containers, Transparency, Consent, and Control (TCC) protections, and hijack third-party apps — all without special permissions or elevated privileges.

[…]

Here’s one interesting aspect of the macOS app sandbox: dragging and dropping a file or folder onto an application grants it unrestricted access to the dropped item. This is by design. Without it, apps couldn’t access files dragged from protected locations like ~/Desktop or ~/Documents, and drag and drop wouldn’t work in sandboxed apps at all.

[…]

Knowing about the drag-and-drop loophole, an attacker can try to convince a user to drag and drop Archive Utility’s preferences file into Terminal, which lets them rewrite Archive Utility’s output folder. From there, copying a file out of an app data container is a two-step move: compress the target file inside a protected area, then extract the archive into a folder the attacker controls.

[…]

Code signing should have prevented this kind of tampering with the application bundle, but for some reason macOS didn’t complain. We would like to investigate this further.

Previously:

• Privacy & Security Settings Don’t Show Intent-Based Access
• macOS 26.4 Paste Protection
• macOS 26.4
• TCC and Gatekeeper Bypasses
• Persistent File Access via com.apple.macl Xattr

Bug Code Signing Exploit Mac macOS Tahoe 26 Sandboxing Security Transparency Consent and Control (TCC)

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