USN-4432-1 fixed vulnerabilities in GRUB2 affecting Secure Boot environments. Unfortunately, the update introduced regressions for some BIOS systems (either pre-UEFI or UEFI configured in Legacy mode), preventing them from successfully booting. This update addresses the issue. Users with BIOS systems that installed GRUB2 versions from USN-4432-1 should verify that their GRUB2 installation has a correct understanding of their boot device location and installed the boot loader correctly. We apologize for the inconvenience.

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).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Detections

Analytics

Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : GRUB2 regression (USN-4432-2)

high Nessus Plugin ID 139365

Version 1.11

Version 1.7

Version 1.11 Oct 21, 2023, 9:06 AM CVSS temporal metrics ("CVSSv2 temporal vector" set to "CVSS2#E:POC/RL:OF/RC:C". "CVSSv3 temporal vector" set to "CVSS:3.0/E:P/RL:O/RC:C") CVSSv3 score source (set to "CVE-2020-10713") Detection Exploit attributes ("Exploit available" set to "True". "Exploitability ease" changed from "No known exploits are available" to "Exploits are available") Plugin metadata Plugin Feed: 202310210906
Version 1.7 Dec 6, 2022, 6:53 AM Reference Plugin Feed: 202212060653