The remote Redhat Enterprise Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2020:3273 advisory.

  - grub2: Crafted grub.cfg file can lead to arbitrary code execution during boot process (CVE-2020-10713)

  - grub2: grub_malloc does not validate allocation size allowing for arithmetic overflow and subsequent heap-     based buffer overflow (CVE-2020-14308)

  - grub2: Integer overflow in grub_squash_read_symlink may lead to heap-based buffer overflow     (CVE-2020-14309)

  - grub2: Integer overflow read_section_as_string may lead to heap-based buffer overflow (CVE-2020-14310)

  - grub2: Integer overflow in grub_ext2_read_link leads to heap-based buffer overflow (CVE-2020-14311)

  - grub2: Fail kernel validation without shim protocol (CVE-2020-15705)

  - grub2: Use-after-free redefining a function whilst the same function is already executing (CVE-2020-15706)

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

The remote Oracle Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2020-5790 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 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 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)

  - 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)

  - 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)

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

This update for grub2 fixes the following issues :

  - CVE-2020-10713 (bsc#1168994)

  - CVE-2020-14308 CVE-2020-14309, CVE-2020-14310,     CVE-2020-14311 (bsc#1173812)

  - CVE-2020-15706 (bsc#1174463)

  - CVE-2020-15707 (bsc#1174570)

  - Use overflow checking primitives where the arithmetic     expression for buffer allocations may include     unvalidated data

  - Use grub_calloc for overflow check and return NULL when     it would occur 

This update was imported from the SUSE:SLE-15-SP1:Update update project.

According to the versions of the grub2 packages installed, the EulerOS Virtualization for ARM 64 installation on the remote host is affected by the following vulnerabilities :

  - 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)

  - 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)

  - 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)

  - 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'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)

  - 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)

  - 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)

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.

ID	名前	製品	ファミリー	公開日	更新日	深刻度
139284	RHEL 7 : grub2 (RHSA-2020:3273)	Nessus	Red Hat Local Security Checks	2020/8/3	2024/4/28	high
180945	Oracle Linux 7 : grub2 (ELSA-2020-5790)	Nessus	Oracle Linux Local Security Checks	2023/9/7	2023/9/8	high
139448	openSUSE Security Update : grub2 (openSUSE-2020-1168)	Nessus	SuSE Local Security Checks	2020/8/10	2024/2/26	high
140948	EulerOS Virtualization for ARM 64 3.0.6.0 : grub2 (EulerOS-SA-2020-2000)	Nessus	Huawei Local Security Checks	2020/9/29	2024/2/19	medium

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