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CentOS 7 : grub2 (RHSA-2020:3217)

high Nessus Plugin ID 139236

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Synopsis

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

Description

The remote CentOS Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2020:3217 advisory.

 - A flaw was found in grub2, prior to version 2.06. An attacker may use the GRUB 2 flaw to hijack and tamper the GRUB verification process. This flaw also allows the bypass of Secure Boot protections. In order to load an untrusted or modified kernel, an attacker would first need to establish access to the system such as gaining physical access, obtain the ability to alter a pxe-boot network, or have remote access to a networked system with root access. With this access, an attacker could then craft a string to cause a buffer overflow by injecting a malicious payload that leads to arbitrary code execution within GRUB. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability. (CVE-2020-10713)

 - In grub2 versions before 2.06 the grub memory allocator doesn't check for possible arithmetic overflows on the requested allocation size. This leads the function to return invalid memory allocations which can be further used to cause possible integrity, confidentiality and availability impacts during the boot process. (CVE-2020-14308)

 - There's an issue with grub2 in all versions before 2.06 when handling squashfs filesystems containing a symbolic link with name length of UINT32 bytes in size. The name size leads to an arithmetic overflow leading to a zero-size allocation further causing a heap-based buffer overflow with attacker controlled data. (CVE-2020-14309)

 - There is an issue on grub2 before version 2.06 at function read_section_as_string(). It expects a font name to be at max UINT32_MAX - 1 length in bytes but it doesn't verify it before proceed with buffer allocation to read the value from the font value. An attacker may leverage that by crafting a malicious font file which has a name with UINT32_MAX, leading to read_section_as_string() to an arithmetic overflow, zero-sized allocation and further heap-based buffer overflow. (CVE-2020-14310)

 - There is an issue with grub2 before version 2.06 while handling symlink on ext filesystems. A filesystem containing a symbolic link with an inode size of UINT32_MAX causes an arithmetic overflow leading to a zero-sized memory allocation with subsequent heap-based buffer overflow. (CVE-2020-14311)

 - GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This only affects systems where the kernel signing certificate has been imported directly into the secure boot database and the GRUB image is booted directly without the use of shim. This issue affects GRUB2 version 2.04 and prior versions. (CVE-2020-15705)

 - GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions. (CVE-2020-15706)

 - Integer overflows were discovered in the functions grub_cmd_initrd and grub_initrd_init in the efilinux component of GRUB2, as shipped in Debian, Red Hat, and Ubuntu (the functionality is not included in GRUB2 upstream), leading to a heap-based buffer overflow. These could be triggered by an extremely large number of arguments to the initrd command on 32-bit architectures, or a crafted filesystem with very large files on any architecture. An attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. This issue affects GRUB2 version 2.04 and prior versions. (CVE-2020-15707)

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

Solution

Update the affected packages.

See Also

https://access.redhat.com/errata/RHSA-2020:3217

Plugin Details

Severity: High

ID: 139236

File Name: centos_RHSA-2020-3217.nasl

Version: 1.9

Type: local

Agent: unix

Published: 7/31/2020

Updated: 10/9/2024

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

Risk Information

VPR

Risk Factor: High

Score: 7.4

Vendor

Vendor Severity: Moderate

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.6

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

CVSS Score Source: CVE-2020-14309

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.4

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

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

CVSS Score Source: CVE-2020-10713

Vulnerability Information

CPE: p-cpe:/a:centos:centos:grub2-common, p-cpe:/a:centos:centos:grub2-ppc64-modules, p-cpe:/a:centos:centos:grub2-efi-x64, p-cpe:/a:centos:centos:grub2-ppc64le-modules, p-cpe:/a:centos:centos:grub2-tools, p-cpe:/a:centos:centos:grub2-ppc64le, p-cpe:/a:centos:centos:fwupdate-devel, p-cpe:/a:centos:centos:grub2-efi-ia32-modules, p-cpe:/a:centos:centos:grub2-ppc64, p-cpe:/a:centos:centos:shim-unsigned-x64, p-cpe:/a:centos:centos:grub2, p-cpe:/a:centos:centos:grub2-efi-ia32-cdboot, p-cpe:/a:centos:centos:grub2-efi-x64-cdboot, p-cpe:/a:centos:centos:grub2-efi-aa64-modules, p-cpe:/a:centos:centos:fwupdate, p-cpe:/a:centos:centos:grub2-tools-extra, p-cpe:/a:centos:centos:shim-x64, p-cpe:/a:centos:centos:mokutil, p-cpe:/a:centos:centos:shim-ia32, p-cpe:/a:centos:centos:grub2-tools-minimal, p-cpe:/a:centos:centos:grub2-pc, p-cpe:/a:centos:centos:grub2-efi-x64-modules, p-cpe:/a:centos:centos:shim-unsigned-ia32, cpe:/o:centos:centos:7, p-cpe:/a:centos:centos:fwupdate-efi, p-cpe:/a:centos:centos:grub2-pc-modules, p-cpe:/a:centos:centos:fwupdate-libs, p-cpe:/a:centos:centos:grub2-ppc-modules, p-cpe:/a:centos:centos:grub2-efi-ia32

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 7/30/2020

Vulnerability Publication Date: 7/29/2020

Reference Information

CVE: CVE-2020-10713, CVE-2020-14308, CVE-2020-14309, CVE-2020-14310, CVE-2020-14311, CVE-2020-15705, CVE-2020-15706, CVE-2020-15707

IAVA: 2020-A-0349

RHSA: 2020:3217