It is quite an interesting vulnerability on many aspects. Among them, and thanks to its hardware basis, it impacts many operating systems. For instance, as long as they run on a Intel processor in long mode (obviously), FreeBSD, NetBSD, Solaris, Xen and Microsoft Windows have been reported to be vulnerable. This therefore gives us quite an incentive to develop an exploit ;).
If you haven’t yet read Xen’s blog post The Intel SYSRET privilege escalation please do because we won’t go again into too much details about the vulnerability itself.
Without further delay, let’s dig right into the FreeBSD exploitation!