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.

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.

All CVEs below are against the SecureBoot functionality in GRUB2. We do not ship this as part of Mageia. Therefore, we ship an updated grub2 package to 2.06 for Mageia 8 fixing upstream bugfixes.

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).

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).

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…

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

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

This update for grub2 fixes the following issue:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

This update was imported from the SUSE:SLE-15-SP2:Update update project.

These are all security issues fixed in the grub2-2.06-7.1 package on the GA media of openSUSE Tumbleweed.

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

This update for grub2 fixes the following issue:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).
• Add fibre channel device's ofpath support to grub-ofpathname and search hint to speed up root device discovery (bsc#1172745).

This update for grub2 fixes the following issues:

• CVE-2020-15705: Fail kernel validation without shim protocol (bsc#1174421).

Jesse Michael and Mickey Shkatov discovered that the configuration parser in GRUB2 did not properly exit when errors were discovered, resulting in heap-based buffer overflows. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-10713)

Chris Coulson discovered that the GRUB2 function handling code did not properly handle a function being redefined, leading to a use-after-free vulnerability. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-15706)

Chris Coulson discovered that multiple integer overflows existed in GRUB2 when handling certain filesystems or font files, leading to heap-based buffer overflows. A local attacker could use these to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-14309, CVE-2020-14310, CVE-2020-14311)

It was discovered that the memory allocator for GRUB2 did not validate allocation size, resulting in multiple integer overflows and heap-based buffer overflows when handling certain filesystems, PNG images or disk metadata. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-14308)

Mathieu Trudel-Lapierre discovered that in certain situations, GRUB2 failed to validate kernel signatures. A local attacker could use this to bypass Secure Boot restrictions. (CVE-2020-15705)

Colin Watson and Chris Coulson discovered that an integer overflow existed in GRUB2 when handling the initrd command, leading to a heap-based buffer overflow. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-15707)