Actually, a response I just gave has important background here:<p><a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11669500" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11669500</a><p>As I went to look up SIP, I found this at the top of the results:<p><a href="https:&#x2F;&#x2F;threatpost.com&#x2F;os-x-zero-day-bypasses-native-sip-protection&#x2F;116984&#x2F;" rel="nofollow">https:&#x2F;&#x2F;threatpost.com&#x2F;os-x-zero-day-bypasses-native-sip-pro...</a><p>So, not looking great so far. ;) Anyway, I decided to look further to find a Wikipedia article on it with what looks to be great description.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;System_Integrity_Protection" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;System_Integrity_Protection</a><p>From what I see, this is Apple&#x27;s answer to the Biba model for integrity protection that&#x27;s intended to divide system up into trust levels where untrustworthy processes can&#x27;t <i>write files</i> they shouldn&#x27;t. This was in Orange Book B1-B3 &amp; A1 class systems such as Compartmented Mode Workstations. LOMAC model, SELinux&#x2F;SEBSD, Windows Integrity Control, Argus PitBull, and Trustifier all implement this scheme to protect files integrity.<p>Let&#x27;s just say it&#x27;s a technique that helps but doesn&#x27;t guarantee security by far. The reason is that the check is in the kernel. That can be bypassed by a 0-day attack on the kernel or below. Trusted processes that manage it might also be hit. Less likely, the person with control over it might be conned into installing something rogue. Seems Apple uses signatures to address that to some degree. So, one tool in the security toolbox just like it was in the 90&#x27;s for CMW&#x27;s. Gotta protect the privileged code and interfaces to it to make sure it&#x27;s not bypassed.<p>One advantage of Biba and similar models are that they&#x27;re conceptually simple plus very efficient in storage and CPU time. I think of it as an extra check to fall back on instead of primary protection. Cost almost nothing. Hope this write-up helps in your assessment of Mac security.