Vulnerability identifier: #VU32926

Vulnerability risk: Low

CVSSv3.1: 5.9 [CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-15706

CWE-ID: CWE-362

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
grub
Universal components / Libraries / Libraries used by multiple products

Vendor: GNU

Description

The vulnerability allows a local attacker to execute arbitrary code and bypass secure boot restriction.

The vulnerability exists due to a race condition in the "grub_script_function_create()" function. An attacker with physical access can exploit the race and execute arbitrary code on the target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

grub: 1.99 - 2.04

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External links
http://ubuntu.com/security/notices/USN-4432-1
http://www.openwall.com/lists/oss-security/2020/07/29/3
http://access.redhat.com/security/vulnerabilities/grub2bootloader
http://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011
http://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass
http://www.debian.org/security/2020/dsa-4735
http://www.debian.org/security/2020-GRUB-UEFI-SecureBoot
http://www.eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/
http://www.openwall.com/lists/oss-security/2020/07/29/3
http://www.suse.com/c/suse-addresses-grub2-secure-boot-issue/
http://www.suse.com/support/kb/doc/?id=000019673

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Q & A

Can this vulnerability be exploited remotely?

No. The attacker should have physical access to the system in order to successfully exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.