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Alibaba Cloud Linux 3 : 0026: grub2 (ALINUX3-SA-2021:0026)

high Nessus Plugin ID 236631

Synopsis

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

Description

The remote Alibaba Cloud Linux 3 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALINUX3-SA-2021:0026 advisory.

 Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

 CVE-2019-14865:
 A flaw was found in the grub2-set-bootflag utility of grub2. A local attacker could run this utility under resource pressure (for example by setting RLIMIT), causing grub2 configuration files to be truncated and leaving the system unbootable on subsequent reboots.

 CVE-2020-10713:
 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-2020-14308:
 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-2020-14309:
 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-2020-14310:
 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-2020-14311:
 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-2020-14372:
 A flaw was found in grub2 in versions prior to 2.06, where it incorrectly enables the usage of the ACPI command when Secure Boot is enabled. This flaw allows an attacker with privileged access to craft a Secondary System Description Table (SSDT) containing code to overwrite the Linux kernel lockdown variable content directly into memory. The table is further loaded and executed by the kernel, defeating its Secure Boot lockdown and allowing the attacker to load unsigned code. The highest threat from this vulnerability is to data confidentiality and integrity, as well as system availability.

 CVE-2020-15705:
 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-2020-25632:
 A flaw was found in grub2 in versions prior to 2.06. The rmmod implementation allows the unloading of a module used as a dependency without checking if any other dependent module is still loaded leading to a use-after-free scenario. This could allow arbitrary code to be executed or a bypass of Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

 CVE-2020-25647:
 A flaw was found in grub2 in versions prior to 2.06. During USB device initialization, descriptors are read with very little bounds checking and assumes the USB device is providing sane values. If properly exploited, an attacker could trigger memory corruption leading to arbitrary code execution allowing a bypass of the Secure Boot mechanism. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

 CVE-2020-27749:
 A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

 CVE-2020-27779:
 A flaw was found in grub2 in versions prior to 2.06. The cutmem command does not honor secure boot locking allowing an privileged attacker to remove address ranges from memory creating an opportunity to circumvent SecureBoot protections after proper triage about grub's memory layout. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

 CVE-2021-20225:
 A flaw was found in grub2 in versions prior to 2.06. The option parser allows an attacker to write past the end of a heap-allocated buffer by calling certain commands with a large number of specific short forms of options. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

 CVE-2021-20233:
 A flaw was found in grub2 in versions prior to 2.06. Setparam_prefix() in the menu rendering code performs a length calculation on the assumption that expressing a quoted single quote will require 3 characters, while it actually requires 4 characters which allows an attacker to corrupt memory by one byte for each quote in the input. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Tenable has extracted the preceding description block directly from the Alibaba Cloud Linux security advisory.

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

http://mirrors.aliyun.com/alinux/3/cve/alinux3-sa-20210026.xml

Plugin Details

Severity: High

ID: 236631

File Name: alinux3_sa_2021-0026.nasl

Version: 1.1

Type: local

Published: 5/14/2025

Updated: 5/14/2025

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 8.1

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.6

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

CVSS Score Source: CVE-2021-20233

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

Vulnerability Information

CPE: p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-ia32, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-pc, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-ia32-cdboot, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-efi-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-aa64-modules, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-aa64-cdboot, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-debugsource, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-extra, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-extra-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-minimal, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-ia32-modules, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-aa64, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-x64-cdboot, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-x64-modules, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-pc-modules, cpe:/o:alibabacloud:alibaba_cloud_linux_3, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-minimal-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-common, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-efi-x64, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:grub2-tools-efi

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/13/2021

Vulnerability Publication Date: 11/29/2019

Reference Information

CVE: CVE-2019-14865, CVE-2020-10713, CVE-2020-14308, CVE-2020-14309, CVE-2020-14310, CVE-2020-14311, CVE-2020-14372, CVE-2020-15705, CVE-2020-25632, CVE-2020-25647, CVE-2020-27749, CVE-2020-27779, CVE-2021-20225, CVE-2021-20233