Mach Race OS X Local Privilege Escalation Exploit
(c) fG! 2015, 2016, reverser@put.as - https://reverse.put.as
A SUID, SIP, and binary entitlements universal OS X exploit (CVE-2016-1757).
Usage against a SUID binary:
./mach_race_server /bin/ps _compat_mode
for i in seq 0 1000000; do ./mach_race_client /bin/ps; done
Against an entitled binary to bypass SIP:
./mach_race_server /System/Library/PrivateFrameworks/PackageKit.framework/Versions/A/Resources/system_shove _geteuid
for i in seq 0 1000000; do ./mach_race_client /System/Library/PrivateFrameworks/PackageKit.framework/Versions/A/Resources/system_shove; done
Note: because the service name is not modified you can't chain this exploit from user to root and then use it to bypass SIP since bootstrap_register2 will fail the second time (service is already registered with launchd from the first run). The solution is to add a parameter to use a different service name for example.
Note2: there's no need to make this into two separate apps, a single binary works, you just need to fork a server and client.
References:
http://googleprojectzero.blogspot.pt/2016/03/race-you-to-kernel.html
Tested against Mavericks 10.10.5, Yosemite 10.10.5, El Capitan 10.11.2 and 10.11.3.
Fixed in El Capitan 10.11.4.
Should work with all OS X versions (depends if bootstrap_register2 exists on older versions).
Alternative implementation with bootstrap_create_server possible for older versions.