AlertsGRUB Security Advisory

Number: AV20-272
Date: 29 July 2020

On 29 July 2020 security researchers publicly disclosed details of a vulnerability in GRUB bootloader. The vulnerability affects all signed versions of GRUB and bypasses UEFI Secure Boot. As GRUB is included in most Linux distributions, this vulnerability can impact most Linux systems.

Exploitation of the vulnerability can be used to perform arbitrary code execution, which can be leveraged to install bootkits that are persistent and difficult to detect.

The Cyber Centre encourages users and administrators to review the provided web link and apply the necessary updates when available:

Microsoft
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011

UEFI Forum
https://uefi.org/revocationlistfile

Debian
https://www.debian.org/security/2020-GRUB-UEFI-SecureBoot

Canonical
https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass

Red Hat
https://access.redhat.com/security/vulnerabilities/grub2bootloader

SUSE
https://www.suse.com/support/kb/doc/?id=000019673

HP
https://techhub.hpe.com/eginfolib/securityalerts/Boot_Hole/boot_hole.html

VMware
https://kb.vmware.com/s/article/80181

Note to Readers
The Canadian Centre for Cyber Security (Cyber Centre) operates as part of the Communications Security Establishment.  We are Canada’s national authority on cyber security and we lead the government’s response to cyber security events. As Canada's national computer security incident response team, the Cyber Centre works in close collaboration with government departments, critical infrastructure, Canadian businesses and international partners to prepare for, respond to, mitigate, and recover from cyber events. We do this by providing authoritative advice and support, and coordinating information sharing and incident response. The Cyber Centre is outward-facing, welcoming partnerships that help build a stronger, more resilient cyber space in Canada.

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