Scientific Linux Security Update : grub2 on SL7.x x86_64

This script is Copyright (C) 2015 Tenable Network Security, Inc.


Synopsis :

The remote Scientific Linux host is missing one or more security
updates.

Description :

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.

- 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.

- 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.

- 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.

- 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.

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.

See also :

http://www.nessus.org/u?9835a4a2

Solution :

Update the affected packages.

Risk factor :

Low / CVSS Base Score : 2.6
(CVSS2#AV:L/AC:H/Au:N/C:P/I:P/A:N)

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 87558 ()

Bugtraq ID:

CVE ID: CVE-2015-5281

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