Actu
Vigil@nce: Linux kernel, denial of service via EFER
April 2009 by Vigil@nce
On an x86 virtualized computer, a local attacker can use EFER to
stop the system.
– Severity: 1/4
– Consequences: denial of service of computer
– Provenance: user shell
– Means of attack: no proof of concept, no attack
– Ability of attacker: expert (4/4)
– Confidence: confirmed by the editor (5/5)
– Diffusion of the vulnerable configuration: high (3/3)
– Creation date: 01/04/2009
IMPACTED PRODUCTS
– Linux kernel
DESCRIPTION OF THE VULNERABILITY
An x86 processor supports VMX (Virtual Machine Extensions).
The vmx_set_msr() function of the arch/x86/kvm/vmx.c file sets MSR
(Model Specific Registers):
– MSR_EFER : extended feature
– MSR_STAR : legacy mode syscall target
– etc.
The EFER MSR is specific to x64 processors. However, in a i386
virtual machine, the vmx_set_msr() function tries to set it, which
panics the kernel.
On an x86 virtualized computer, a local attacker can therefore use
EFER to stop the system.
CHARACTERISTICS
– Identifiers: VIGILANCE-VUL-8585
– Url: http://vigilance.fr/vulnerability/Linux-kernel-denial-of-service-via-EFER-8585
