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Добавлено: 13 май 2015, 08:21
https://access.redhat.com/articles/1444903
Red Hat Product Security has been made aware of a 'buffer overflow' vulnerability affecting the Floppy Disk Controller (FDC) emulation implemented in the QEMU component of the KVM/QEMU and Xen hypervisors. The vulnerability, which has been assigned CVE-2015-3456 and is now being referred to as VENOM, was discovered by Jason Geffner of CrowdStrike, Inc. The vulnerability was rated as having an Important impact.
Background Information
QEMU is a generic and open source machine emulator and virtualizer and is incorporated in some Red Hat products as a foundation and hardware emulation layer for running virtual machines under the Xen and KVM/QEMU hypervisors.
Impact
A privileged guest user could use this flaw to crash the guest or, potentially, execute arbitrary code on the host with the privileges of the host's QEMU process corresponding to the guest. It needs to be noted that even if a guest does not explicitly have a virtual floppy disk configured and attached, this issue is exploitable. The problem exists in the Floppy Disk Controller, which is initialized for every x86 and x86_64 guest regardless of the configuration and cannot be removed or disabled.
There is currently no known exploit that would make use of this vulnerability. The sVirt and seccomp functionalities used to restrict host's QEMU process privileges and resource access might mitigate the impact of successful exploitation of this issue. A possible policy-based workaround is to avoid granting untrusted users administrator privileges within guests.