Vigil@nce - Xen: privilege escalation via SYSCALL
February 2017 by Vigil@nce
This bulletin was written by Vigil@nce : https://vigilance.fr/offer
SYNTHESIS OF THE VULNERABILITY
An attacker can trigger a debug trap on a SYSCALL instruction in a
guest system managed by Xen, in order to get guest operating
system privileges on non Linux systems.
Impacted products: Debian, Fedora, openSUSE, openSUSE Leap, SUSE
Linux Enterprise Desktop, SLES, Xen.
Severity: 2/4.
Creation date: 20/12/2016.
DESCRIPTION OF THE VULNERABILITY
Processing the interrupts, exceptions and traps is part of the job
of the hypervisor Xen.
A user program like a debugger in a guest system can define the
conditions that trigger debug traps. However, Xen wrongly handles
one of these traps when it applies to a SYSCALL instruction, which
triggers a privilege transition as part of the processing of
system calls.
An attacker can therefore trigger a debug trap on a SYSCALL
instruction in a guest system managed by Xen, in order to get
guest operating system privileges on non Linux systems.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
https://vigilance.fr/vulnerability/Xen-privilege-escalation-via-SYSCALL-21423