Apple macOS - 'stackshot' Raw Frame Pointers

EDB-ID: 42047
Author: Google Security Research
Published: 2017-05-22
CVE: CVE-2017-2516
Type: Dos
Platform: macOS
Aliases: N/A
Advisory/Source: Link
Tags: N/A
Vulnerable App: N/A

  
This is an issue that allows unentitled root to read kernel frame
pointers, which might be useful in combination with a kernel memory
corruption bug.

By design, the syscall stack_snapshot_with_config() permits unentitled
root to dump information about all user stacks and kernel stacks.
While a target thread, along with the rest of the system, is frozen,
machine_trace_thread64() dumps its kernel stack.
machine_trace_thread64() walks up the kernel stack using the chain of
saved RBPs. It dumps the unslid kernel text pointers together with
unobfuscated frame pointers.

The attached PoC dumps a stackshot into the file stackshot_data.bin
when executed as root. The stackshot contains data like this:

00000a70 de 14 40 00 80 ff ff ff a0 be 08 77 80 ff ff ff |..@........w....|
00000a80 7b b8 30 00 80 ff ff ff 20 bf 08 77 80 ff ff ff |{.0..... ..w....|
00000a90 9e a6 30 00 80 ff ff ff 60 bf 08 77 80 ff ff ff |..0.....`..w....|
00000aa0 5d ac 33 00 80 ff ff ff b0 bf 08 77 80 ff ff ff |].3........w....|

The addresses on the left are unslid kernel text pointers; the
addresses on the right are valid kernel stack pointers.


Proof of Concept:
https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/42047.zip

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