You may ask; "why would Apple add an XPC service that can create setuid files anywhere on the system - and then blindly allow any local user to leverage this service?" Honestly, I have no idea!
The undocumented 'writeconfig' XPC service was recently uncovered by Emil Kvarnhammar, who determined its lax controls could be abused to escalate one's privileges to root. Dubbed ‘rootpipe,' this bug was patched in OS X 10.10.3. End of story, right? Nope, instead things then got quite interesting. First, Apple decided to leave older versions of OS X un-patched. Then, an astute researcher discovered that the OSX/XSLCmd malware which pre-dated the disclosure, exploited this same vulnerability as a 0day! Finally, yours truly, found a simple way to side-step Apple's patch to re-exploit the core vulnerability on a fully-patched system. So come attend (but maybe leave your MacBooks at home), as we dive into the technical details XPC and the rootpipe vulnerability, explore how malware exploited this flaw, and then fully detail the process of completely bypassing Apple's patch. The talk will conclude by examining Apple’s response, a second patch, that appears to squash ‘rootpipe’…for now.