Secure Boot bypass via unlocked cutmem command
Published Mar 3, 2021 · Updated Aug 4, 2024
Improper authorization in GNU GRUB before 2.06 allows local users with high privileges to bypass Secure Boot through the cutmem command. The command remains available under Secure Boot lockdown and removes attacker-chosen physical address ranges from GRUB's memory map without enforcing the lock. Exploitation requires privileged access and knowledge of the bootloader's memory layout; successful use weakens boot-chain integrity and can expose, alter, or interrupt protected system state.
Summary
What happened
Improper authorization in GNU GRUB before 2.06 allows local users with high privileges to bypass Secure Boot through the cutmem command. The command remains available under Secure Boot lockdown and removes attacker-chosen physical address ranges from GRUB's memory map without enforcing the lock. Exploitation requires privileged access and knowledge of the bootloader's memory layout; successful use weakens boot-chain integrity and can expose, alter, or interrupt protected system state.
The record
- CVE
- CVE-2020-27779
- Published
- Mar 3, 2021
- Updated
- Aug 4, 2024
- Vendor
- The GnuPG Project
- Product
- GNU GRUB
- Classifications
- CWE-285, T1542.003
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Mar 3, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=grub 2.06
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Public exploit references
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Technologies
Your stack
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Your stack
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