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Ubuntu 20.04 LTS: USN-4432-1 Critical: GRUB 2 Buffer Overflow Threat

Several security issues were fixed in GRUB 2.. =========================================================================Ubuntu Security Notice USN-4432-1 July 29, 2020 grub2, grub2-signed vulnerabilities ========================================================================= A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 20.04 LTS - Ubuntu 18.04 LTS - Ubuntu 16.04 LTS - Ubuntu 14.04 ESM Summary: Several security issues were fixed in GRUB 2. Software Description: - grub2: GRand Unified Bootloader - grub2-signed: GRand Unified Bootloader Details: 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) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 20.04 LTS: grub-efi-amd64-bin 2.04-1ubuntu26.1 grub-efi-amd64-signed 1.142.3+2.04-1ubuntu26.1 grub-efi-arm-bin 2.04-1ubuntu26.1 grub-efi-arm64-bin 2.04-1ubuntu26.1 grub-efi-arm64-signed 1.142.3+2.04-1ubuntu26.1 grub-efi-ia32-bin 2.04-1ubuntu26.1 Ubuntu 18.04 LTS: grub-efi-amd64-bin 2.02-2ubuntu8.16 grub-efi-amd64-signed 1.93.18+2.02-2ubuntu8.16 grub-efi-arm-bin 2.02-2ubuntu8.16 grub-efi-arm64-bin 2.02-2ubuntu8.16 grub-efi-arm64-signed 1.93.18+2.02-2ubuntu8.16 grub-efi-ia32-bin 2.02-2ubuntu8.16 grub-efi-ia64-bin 2.02-2ubuntu8.16 Ubuntu 16.04 LTS: grub-efi-amd64-bin 2.02~beta2-36ubuntu3.26 grub-efi-amd64-signed 1.66.26+2.02~beta2-36ubuntu3.26 grub-efi-arm-bin 2.02~beta2-36ubuntu3.26 grub-efi-arm64-bin 2.02~beta2-36ubuntu3.26 grub-efi-arm64-signed 1.66.26+2.02~beta2-36ubuntu3.26 grub-efi-ia32-bin 2.02~beta2-36ubuntu3.26 grub-efi-ia64-bin 2.02~beta2-36ubuntu3.26 Ubuntu 14.04 ESM: grub-efi-amd64-bin 2.02~beta2-9ubuntu1.20 grub-efi-amd64-signed 1.34.22+2.02~beta2-9ubuntu1.20 grub-efi-arm-bin 2.02~beta2-9ubuntu1.20 grub-efi-arm64-bin 2.02~beta2-9ubuntu1.20 grub-efi-ia32-bin 2.02~beta2-9ubuntu1.20 grub-efi-ia64-bin 2.02~beta2-9ubuntu1.20 Fully mitigating these vulnerabilities requires bothan updated GRUB2 boot loader and the application of a UEFI Revocation List (dbx) to system firmware. Ubuntu will provide a packaged dbx update at a later time, though system adminstrators may choose to apply a third party dbx update before then. For more details on mitigation steps and the risks entailed (especially for dual/multi-boot scenarios), please see the Knowledge Base article at https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass References: https://ubuntu.com/security/notices/USN-4432-1 CVE-2020-10713, CVE-2020-14308, CVE-2020-14309, CVE-2020-14310, CVE-2020-14311, CVE-2020-15705, CVE-2020-15706, CVE-2020-15707, https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass Package Information: https://launchpad.net/ubuntu/+source/grub2/2.04-1ubuntu26.1 https://launchpad.net/ubuntu/+source/grub2-signed/1.142.3 https://launchpad.net/ubuntu/+source/grub2/2.02-2ubuntu8.16 https://launchpad.net/ubuntu/+source/grub2-signed/1.93.18 https://launchpad.net/ubuntu/+source/grub2/2.02~beta2-36ubuntu3.26 https://launchpad.net/ubuntu/+source/grub2-signed/1.66.26 . Enhancements to GRUB 2 in Ubuntu address various critical vulnerabilities, providing comprehensive instructions on implementation.. GRUB 2 Issue Resolution, Linux Security Notice, Ubuntu Security Recommendations. . Severity: Critical. LinuxSecurity.com Team

Jul 29, 2020 •Critical Ubuntu