Mach Race OSX - Local Privilege Escalation

Type exploitpack
Reporter fG!
Modified 2016-04-27T00:00:00


Mach Race OSX - Local Privilege Escalation


Mach Race OS X Local Privilege Escalation Exploit

(c) fG! 2015, 2016, -

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.


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.

Proof of Concept: