fileIsSafe() returned true unconditionally on win32 ('ACL check is a
follow-up'), leaving the best-effort directory DACL as the only guard on
what the runner imports and executes. The follow-up: before importing a
unit, read its SDDL (Get-Acl via the full-System32-path powershell) and
refuse loudly — exactly like the Unix mode-bits path — unless the owner
is SYSTEM/Administrators/TrustedInstaller (or the account the runner
itself runs as, mirroring Unix's 'your own file is fine') and no other
principal holds a write-capable allow ACE (write/append data, EA/attrs,
DELETE, WRITE_DAC, WRITE_OWNER, generic write/all).
The SDDL verdict is a pure exported function with platform-independent
tests; unknown ACE shapes and unreadable ACLs fail closed. Inherit-only
ACEs (templates for children) and deny ACEs don't trip it.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
7fe07d0fa5