GRUB2 boot loader maintainers fixed hundreds of flaws
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-10713 | A flaw was found in grub2, prior to version 2.06. 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. NVD description · AI analysis pending | 8.2 | 2% |
| — | ||
| CVE-2020-25632 | A flaw was found in grub2 in versions prior to 2.06. 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. NVD description · AI analysis pending | 8.2 group max | 1% |
| — | ||
| CVE-2020-15705 | GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. 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. NVD description · AI analysis pending | 6.4 | 1% |
| — | ||
| CVE-2021-3418 | If certificates that signed grub are installed into db, grub can be booted directly. If certificates that signed grub are installed into db, grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown, yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism. NVD description · AI analysis pending | 6.4 | <1% |
| — |
Full article594 words · extracted from securityaffairs.com · click to collapse
Now maintainers at the GRUB project have released security updates to address more than 100 vulnerabilities.
GRUB2 (the GRand Unified Bootloader version 2) is a replacement for the original GRUB Legacy boot loader, which is now referred to as “GRUB Legacy”. The mechanism is designed to protect the boot process from attacks.
In July 2020, researchers at the cybersecurity firmware Eclypsium disclosed a buffer overflow vulnerability, tracked as CVE-2020-10713 and dubbed BootHole, which can be exploited by attackers to install persistent and stealthy malware.
Now maintainers at the GRUB project have released security updates to address more than 100 vulnerabilities.
“The BootHole vulnerability [announced last year encouraged many people to take a closer look at the security of boot process in general and the GRUB bootloader in particular. Due to that, during past few months we were getting reports of, and also discovering various security flaws in the GRUB ourselves.” wrote GRUB maintainer Daniel Kiper on GRUB’s mailing list. “You can find the list of most severe ones which got CVEs assigned at the end of this message. The patch bundle fixing all these issues in the upstream GRUB contains 117 patches.”
The GRUB project maintainers released a total of 117 upstream code patches for the above flaws.
Below the list of GRUB2 vulnerabilities shared in the newsletter:
- CVE-2020-14372 grub2: The acpi command allows privileged user to load crafted ACPI tables when Secure Boot is enabled CWE-184 (CVSS 7.5) – Reported by Máté Kukri.
- CVE-2020-25632 grub2: Use-after-free in rmmod command CWE-416 (CVSS 7.5) – Reported by Chris Coulson (Canonical).
- CVE-2020-25647 grub2: Out-of-bound write in grub_usb_device_initialize() CWE-787 (CVSS 6.9). – Reported-by: Joseph Tartaro (IOActive) and Ilja van Sprundel (IOActive).
- CVE-2020-27749 grub2: Stack buffer overflow in grub_parser_split_cmdline CWE-121(CVSS 7.5) – Reported-by: Chris Coulson (Canonical).
- CVE-2020-27779 grub2: The cutmem command allows privileged user to remove memory regions when Secure Boot is enabled CWE-285 (CVSS 7.5) – Reported-by: Teddy Reed.
- CVE-2021-3418 – grub2: GRUB 2.05 reintroduced CVE-2020-15705 CWE-281 (CVSS 6.4) – Reported-by: Dimitri John Ledkov (Canonical).
- CVE-2021-20225 grub2: Heap out-of-bounds write in short form option parser CWE-787 (CVSS 7.5) – Reported-by: Daniel Axtens (IBM).
- CVE-2021-20233 grub2: Heap out-of-bound write due to mis-calculation of space required for quoting. (CVSS 7.5) – Reported-by: Daniel Axtens (IBM)
“In addition, we have been working on a generation number based revocation scheme termed UEFI Secure Boot Advanced Targeting (SBAT) [3]. This will require an UEFI dbx release and resigning all the artifacts — shim, GRUB, kernel, etc. — needed to boot the system. This is the same as we did for the BootHole series of vulnerabilities, but the SBAT work is designed to make this process much less painful in the future.” Kiper added. “Details of exactly what needs updating will be provided by the respective distros and vendors when updates become available. Here [4] we are listing at least some links to the messaging known at the time of this posting.”
Major Linux distros, including Debian, RedHat, and Ubuntu, released security advisories for the above vulnerabilities.
“Details of exactly what needs updating will be provided by the respective distros and vendors when updates become available.” concluded Kiper.
“Full mitigation against all the CVEs will require an updated UEFI revocation list (dbx) which, in at least some cases, will not allow Secure Boot with today’s boot artifacts.”
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