Xen Arm-Based CPU Speculation past the ERET Instruction (XSA-312)

medium Nessus Plugin ID 134307

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Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a speculative memory accesses vulnerability. Some CPUs can speculate past an ERET instruction and potentially perform speculative accesses to memory before processing the exception return. Since the register state is often controlled by lower privilege level (i.e guest kernel/userspace) at the point of the ERET. An attacker, which could include a malicious untrusted user process on a trusted guest, or an untrusted guest, may be able to use it as part of side-channel attack to read host memory. System running all version of Xen are affected. An individual Arm-based CPU is vulnerable depending on its speculation properties, while x86 systems are not vulnerable.

Solution

Apply the appropriate patch or workaround according to the vendor advisory.

Plugin Details

Severity: Medium

ID: 134307

File Name: xen_server_XSA-312.nasl

Version: 1.1

Type: local

Family: Misc.

Published: 3/6/2020

Updated: 3/6/2020

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

CVSS Score Rationale: Based on analysis of the vendor advisory.

CVSS v2

Risk Factor: Medium

Base Score: 4.4

Vector: CVSS2#AV:L/AC:M/Au:S/C:C/I:N/A:N

CVSS Score Source: manual

CVSS v3

Risk Factor: Medium

Base Score: 5.6

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: Settings/ParanoidReport, installed_sw/Xen Hypervisor

Patch Publication Date: 2/14/2020

Vulnerability Publication Date: 1/14/2020

Detections

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