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Comment by qwertyoruiop | Hacker News Reader

If the heap info leak fails, I bail out cleanly. If the kASLR leak fails, it is usually because instead of hitting a vm_map_copy (the intended structure I need to corrupt), something completely unrelated is hit instead. If it happens to hit something different than expected, that's undefined behaviour usually ending up in a panic.

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Mad props.

If osx were s/xnu/minix 3-style, full microkernel/, sploiting Iokit as a least priv'd process, only it would get pwned and be limited to iokit's acls. Still bad, but it likely wouldnt have rights to exec a root shell.

XNU kexts have way too much authority, and all the syscalls they each tack on compounds the attack surface to the total codebases of all Apple and third-party kexts. Because once you've found and symbolicated the not-really-hidden call table, you're pretty much able to do whatever. And with a mutating mem kext bug ...

while I agree with you on the security benefits of a full microkernel, to be entirely honest, if you had access to just IOKit you could easily use a network card or an hard drive controller to get a physical memory write-what-where, which in turn would allow you to gain access to anything, plus the microkernel performance issues of e.g. having to context switch on interrupts.

That things may be broken is no argument against defense-in-depth and least privilege. By having smaller codebases and smaller system components, the attack surface is far, far smaller than say Linux. IOKit is shit as is, and a full microkernel would break it up into processes based on areas of responsibility. Also, that shows the hardware needs better bus- and command-level security to prevent such attacks. (Don't even get me started on closed firmware blobs or unverifiability of commercial cores.)

Expecting a finished product of a new project would be unreasonable. Minix 3 is early on and not the only full microkernel out there. They will probably find an approach to reduce context switches if it's a mature optimization to make. An Android-like mobile/embedded platform would make a sensible research -> real use-case, minus Java.

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