RHEL 7 : grub2 (RHSA-2015:2401)

critical Nessus Plugin ID 86989

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Synopsis

The remote Red Hat host is missing a security update.

Description

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2015:2401 advisory.

The grub2 packages provide version 2 of the Grand Unified Bootloader (GRUB), a highly configurable and customizable bootloader with modular architecture. The packages support a variety of kernel formats, file systems, computer architectures, and hardware devices.

It was discovered that grub2 builds for EFI systems contained modules that were not suitable to be loaded in a Secure Boot environment. An attacker could use this flaw to circumvent the Secure Boot mechanisms and load non-verified code. Attacks could use the boot menu if no password was set, or the grub2 configuration file if the attacker has root privileges on the system. (CVE-2015-5281)

This update also fixes the following bugs:

* In one of the earlier updates, GRUB2 was modified to escape forward slash (/) characters in several different places. In one of these places, the escaping was unnecessary and prevented certain types of kernel command-line arguments from being passed to the kernel correctly. With this update, GRUB2 no longer escapes the forward slash characters in the mentioned place, and the kernel command-line arguments work as expected. (BZ#1125404)

* Previously, GRUB2 relied on a timing mechanism provided by legacy hardware, but not by the Hyper-V Gen2 hypervisor, to calibrate its timer loop. This prevented GRUB2 from operating correctly on Hyper-V Gen2.
This update modifies GRUB2 to use a different mechanism on Hyper-V Gen2 to calibrate the timing. As a result, Hyper-V Gen2 hypervisors now work as expected. (BZ#1150698)

* Prior to this update, users who manually configured GRUB2 to use the built-in GNU Privacy Guard (GPG) verification observed the following error on boot:

alloc magic is broken at [addr]: [value] Aborted.

Consequently, the boot failed. The GRUB2 built-in GPG verification has been modified to no longer free the same memory twice. As a result, the mentioned error no longer occurs. (BZ#1167977)

* Previously, the system sometimes did not recover after terminating unexpectedly and failed to reboot. To fix this problem, the GRUB2 packages now enforce file synchronization when creating the GRUB2 configuration file, which ensures that the required configuration files are written to disk. As a result, the system now reboots successfully after crashing.
(BZ#1212114)

* Previously, if an unconfigured network driver instance was selected and configured when the GRUB2 bootloader was loaded on a different instance, GRUB2 did not receive notifications of the Address Resolution Protocol (ARP) replies. Consequently, GRUB2 failed with the following error message:

error: timeout: could not resolve hardware address.

With this update, GRUB2 selects the network driver instance from which it was loaded. As a result, ARP packets are processed correctly. (BZ#1257475)

In addition, this update adds the following enhancement:

* Sorting of GRUB2 boot menu has been improved. GRUB2 now uses the rpmdevtools package to sort available kernels and the configuration file is being generated correctly with the most recent kernel version listed at the top. (BZ#1124074)

All grub2 users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

Plugin Details

Severity: Critical

ID: 86989

File Name: redhat-RHSA-2015-2401.nasl

Version: 2.12

Type: local

Agent: unix

Family: Red Hat Local Security Checks

Published: 11/20/2015

Updated: 11/4/2024

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

Vendor

Vendor Severity: Low

CVSS v2

Risk Factor: Low

Base Score: 2.6

Temporal Score: 1.9

Vector: CVSS2#AV:L/AC:H/Au:N/C:P/I:P/A:N

CVSS Score Source: CVE-2015-5281

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:redhat:enterprise_linux:grub2-efi, cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:redhat:enterprise_linux:grub2-tools, p-cpe:/a:redhat:enterprise_linux:grub2-efi-modules, p-cpe:/a:redhat:enterprise_linux:grub2

Required KB Items: Host/local_checks_enabled, Host/RedHat/release, Host/RedHat/rpm-list, Host/cpu

Exploit Ease: No known exploits are available

Patch Publication Date: 11/19/2015

Vulnerability Publication Date: 11/24/2015

Reference Information

CVE: CVE-2015-5281

RHSA: 2015:2401

Detections

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