This update for grub2 fixes the following issues :

grub2 now implements the new 'SBAT' method for SHIM based secure boot revocation. (bsc#1182057)

Following security issues are fixed that can violate secure boot constraints :

CVE-2020-25632: Fixed a use-after-free in rmmod command (bsc#1176711)

CVE-2020-25647: Fixed an out-of-bound write in grub_usb_device_initialize() (bsc#1177883)

CVE-2020-27749: Fixed a stack-based buffer overflow in grub_parser_split_cmdline (bsc#1179264)

CVE-2020-27779, CVE-2020-14372: Disallow cutmem and acpi commands in secure boot mode (bsc#1179265 bsc#1175970)

CVE-2021-20225: Fixed a heap out-of-bounds write in short form option parser (bsc#1182262)

CVE-2021-20233: Fixed a heap out-of-bound write due to mis-calculation of space required for quoting (bsc#1182263)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:1734 advisory.

  - grub2: acpi command allows privileged user to load crafted ACPI tables when Secure Boot is enabled     (CVE-2020-14372)

  - grub2: Use-after-free in rmmod command (CVE-2020-25632)

  - grub2: Out-of-bounds write in grub_usb_device_initialize() (CVE-2020-25647)

  - grub2: Stack buffer overflow in grub_parser_split_cmdline() (CVE-2020-27749)

  - grub2: cutmem command allows privileged user to remove memory regions when Secure Boot is enabled     (CVE-2020-27779)

  - grub2: Heap out-of-bounds write in short form option parser (CVE-2021-20225)

  - grub2: Heap out-of-bounds write due to miscalculation of space required for quoting (CVE-2021-20233)

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

The remote NewStart CGSL host, running version CORE 5.04 / MAIN 5.04, has grub2 packages installed that are affected by multiple vulnerabilities:

  - 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-2020-14372)

  - 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-2020-25632)

  - 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-2020-25647)

  - 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-2020-27749)

  - 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-2020-27779)

  - 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-2021-20225)

  - 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. (CVE-2021-20233)

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

The remote CentOS Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the CESA-2021:0696 advisory.

  - grub2: acpi command allows privileged user to load crafted ACPI tables when Secure Boot is enabled     (CVE-2020-14372)

  - grub2: Use-after-free in rmmod command (CVE-2020-25632)

  - grub2: Out-of-bounds write in grub_usb_device_initialize() (CVE-2020-25647)

  - grub2: Stack buffer overflow in grub_parser_split_cmdline() (CVE-2020-27749)

  - grub2: cutmem command allows privileged user to remove memory regions when Secure Boot is enabled     (CVE-2020-27779)

  - grub2: Heap out-of-bounds write in short form option parser (CVE-2021-20225)

  - grub2: Heap out-of-bounds write due to miscalculation of space required for quoting (CVE-2021-20233)

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

An update of the grub2 package has been released.

According to the versions of the grub2 packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

  - 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-2020-27779)

  - 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-2020-14372)

  - 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-2020-25632)

  - 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-2021-20225)

  - 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.(CVE-2021-20233)

  - 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-2020-27749)

  - 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-2020-25647)

  - ** RESERVED ** This candidate has been reserved by an     organization or individual that will use it when     announcing a new security problem. When the candidate     has been publicized, the details for this candidate     will be provided.(CVE-2020-17779)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the versions of the grub2 packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - 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-2020-27779)

  - 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-2020-14372)

  - 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-2020-25632)

  - 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-2021-20225)

  - 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.(CVE-2021-20233)

  - 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-2020-27749)

  - 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-2020-25647)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Windows host is missing an update to the Secure Boot DBX. It is, therefore, affected by multiple vulnerabilities:

  - 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-2020-25632)

  - 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. (CVE-2021-20233)


Additionally, the host is affected by several other security feature bypasses in Secure Boot.

Note: Tenable is testing for the presence of the expected signatures added in the DBX update published on March 2, 2021 referenced in the vendor advisory.

ID	Name	Product	Family	Published	Updated	Severity
146976	SUSE SLES12 Security Update : grub2 (SUSE-SU-2021:0682-1)	Nessus	SuSE Local Security Checks	3/3/2021	1/18/2024	high
146978	SUSE SLES15 Security Update : grub2 (SUSE-SU-2021:0684-1)	Nessus	SuSE Local Security Checks	3/3/2021	1/18/2024	high
149687	RHEL 8 : shim (RHSA-2021:1734)	Nessus	Red Hat Local Security Checks	5/19/2021	1/1/2024	high
154609	NewStart CGSL CORE 5.04 / MAIN 5.04 : grub2 Multiple Vulnerabilities (NS-SA-2021-0097)	Nessus	NewStart CGSL Local Security Checks	10/28/2021	11/27/2023	high
146965	CentOS 8 : grub2 (CESA-2021:0696)	Nessus	CentOS Local Security Checks	3/3/2021	1/18/2024	high
148024	Photon OS 4.0: Grub2 PHSA-2021-4.0-0001	Nessus	PhotonOS Local Security Checks	3/24/2021	1/8/2024	high
148618	EulerOS Virtualization 2.9.1 : grub2 (EulerOS-SA-2021-1714)	Nessus	Huawei Local Security Checks	4/15/2021	1/4/2024	high
150210	EulerOS 2.0 SP9 : grub2 (EulerOS-SA-2021-1927)	Nessus	Huawei Local Security Checks	6/3/2021	12/27/2023	high
139239	Windows Security Feature Bypass in Secure Boot (BootHole)	Nessus	Windows	7/31/2020	4/29/2024	high

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