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I had actually submitted to the ZDI, but had written the exploit & write-up in the first place mainly because I like hacking rather than for money. I figured I'd see what offers I'd get anyway, but once I had spent all the time on the write-up, I mainly wanted people to see that, and the amount offered wasn't enough to convince me otherwise. I might've published this earlier even, but my December was kinda busy, first with the v0rtex exploit and then with 34C3.

And an engineer from Apple's security team contacted me a bit after releasing - they had found the bug a while ago, but hadn't verified the subsequent patch which actually didn't fix it. And a while ago I tweeted this https://twitter.com/s1guza/status/921889566549831680 (try diff'ing sources to find it :P). So they do have people on it. I also told that person to extend my condolences to whoever has to come in and fix that now, but they basically said that there's nothing to apologise for and that they (the team) really like such write-ups. So... I guess I'm not that evil?

And I neither wanna watch the world burn nor did anyone brush me the wrong way - I didn't publish this out of hate, but out of love for hacking. If you're concerned about skids hacking you now, they need to get code execution first on your machine. If you're concerned about people who can do that, then those can also get kernel r/w without me, so... nothing really changed for the average user.

PS: Yes, it's really me. Will add keybase proof if my karma gets >= 2. Edit: done, see my profile.




The write-up you did on this vulnerability (not to mention the discovery of the vulnerability and coming up with a working exploit) is really top notch. Thanks for taking the time to compose such a high-quality explanation and walk-through.


Incredible work. How did you find the bug and how many hours did it take you in total?


I found it by looking through IOHIDFamily's source, hoping to find a low-hanging fruit affecting iOS. In total? A lot, probably way too much... I had found it in February and started to write an exploit in April. Next to my studies, exams, the Phœnix Jailbreak and Apple trying to mitigate tfp0, it took me until August to get a fully working exploit, at which point I figured I'd wait for High Sierra. And that actually broke a bunch of stuff (heap layout assumptions, ROP gadgets, kernel symbols, ...) so I had to fix these. In October I started working on the write-up, but when I got to the part about the info leak, I had written that it's most likely possible, but I had no demo for that. I didn't wanna leave an empty claim stand there like that, so I ended up taking another month to get the "leak" binary working and basically write a second exploit. By that time it was early November - the write-up with its graphs took some time and before I knew it, December had started (at which point I was finally done). All in all probably 200-250h - but it was a hard-to-exploit bug (IMO), I've done way more than necessary, and when I started I had still rather little knowledge of XNU and required a lot of time to learn how most stuff worked. Especially everything from the "leak" part was later really useful for v0rtex, whose initial version took me just one and a half days then - without that work, it would've taken me a couple of weeks at least.


If Apple doesn't offer you a job they're insane.


That was my thought too. As an apple customer (5+ macs and 10+ i-Devices), I'd feel way better knowing that apple cares about macOS security enough to hire skilled engineers.


I'm a total non-engineer/developer, but I'm increasingly interested in what guys like you think about software QA as it relates to security.

Today's Apple does a lot of security posturing in hardware/platform architecture, like full disk encryption, the iOS device secure enclave thingie, the secure enclave's subsequent inclusion on touchbar Macbook Pros to control the webcam, iOS defaulting to non-networked sandboxing for third party keyboards, etc.

Do you think macOS/iOS development perhaps should slow down from a yearly release cycle to delay releases with continuous big reworking starting with XNU?

With a very rudimentary outsider perspective on QA, it just seems insane to keep pushing big OS changes yearly.


You say you submitted it to the ZDI, but did you try sending it to Apple product security?


No, their bug bounty only extends to iOS.


Doesn't mean you can't email product-security@apple.com with your bug anyway.


Why, if they clearly place no [monetary] value on security of OSX?


I suggest contact Google's Project Zero. I think those guys would love to help you...




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