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Amazon Linux 2 : grub2 (ALAS-2021-1684)
high Nessus Plugin ID 151799
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Synopsis
The remote Amazon Linux 2 host is missing a security update.Description
The version of grub2 installed on the remote host is prior to 2.06-2. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2021-1684 advisory.2024-02-29: CVE-2019-14865 was added to this advisory.
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-2019-14865)
A flaw was found in GRUB 2, 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-2020-14372)
A flaw was found in grub2. 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-2020-25632)
A flaw was found in grub2. 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-2020-25647)
A flaw was found in grub2. 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-2020-27749)
A flaw was found in grub2. 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-2020-27779)
A flaw was found in grub2. 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-2021-20225)
A flaw was found in grub2. 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. (CVE-2021-20233)
Tenable has extracted the preceding description block directly from the tested product 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
Run 'yum update grub2' to update your system.See Also
https://alas.aws.amazon.com/AL2/ALAS-2021-1684.html
https://alas.aws.amazon.com/cve/html/CVE-2019-14865.html
https://alas.aws.amazon.com/cve/html/CVE-2020-14372.html
https://alas.aws.amazon.com/cve/html/CVE-2020-25632.html
https://alas.aws.amazon.com/cve/html/CVE-2020-25647.html
https://alas.aws.amazon.com/cve/html/CVE-2020-27749.html
https://alas.aws.amazon.com/cve/html/CVE-2020-27779.html
https://alas.aws.amazon.com/cve/html/CVE-2021-20225.html
Plugin Details
Severity: High
ID: 151799
File Name: al2_ALAS-2021-1684.nasl
Version: 1.6
Type: local
Agent: unix
Published: 7/16/2021
Updated: 12/11/2024
Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus
Risk Information
VPR
Risk Factor: High
Score: 7.3
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:amazon:linux:grub2-efi-aa64, p-cpe:/a:amazon:linux:grub2-tools-efi, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:grub2-efi-aa64-modules, p-cpe:/a:amazon:linux:grub2-efi-aa64-ec2, p-cpe:/a:amazon:linux:grub2-emu, p-cpe:/a:amazon:linux:grub2-tools-extra, p-cpe:/a:amazon:linux:grub2-efi-aa64-cdboot, p-cpe:/a:amazon:linux:grub2-efi-x64-modules, p-cpe:/a:amazon:linux:grub2-pc-modules, p-cpe:/a:amazon:linux:grub2-efi-x64, p-cpe:/a:amazon:linux:grub2, p-cpe:/a:amazon:linux:grub2-common, p-cpe:/a:amazon:linux:grub2-pc, p-cpe:/a:amazon:linux:grub2-tools-minimal, p-cpe:/a:amazon:linux:grub2-tools, p-cpe:/a:amazon:linux:grub2-efi-x64-ec2, p-cpe:/a:amazon:linux:grub2-emu-modules, p-cpe:/a:amazon:linux:grub2-debuginfo, p-cpe:/a:amazon:linux:grub2-efi-x64-cdboot
Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list
Exploit Available: true
Exploit Ease: Exploits are available
Patch Publication Date: 7/14/2021
Vulnerability Publication Date: 7/30/2020
Reference Information
CVE: CVE-2019-14865, CVE-2020-14372, CVE-2020-25632, CVE-2020-25647, CVE-2020-27749, CVE-2020-27779, CVE-2021-20225, CVE-2021-20233
ALAS: 2021-1684
IAVA: 2020-A-0349