Περισσότερα από 25 μοντέλα φορητών υπολογιστών της Lenovo είναι ευάλωτα σε κακόβουλες επιθέσεις που disable the UEFI secure boot process and then run unsigned UEFI apps or load bootloaders to permanently backdoor devices.
At the same time that researchers from security firm ESET uncovered the vulnerabilities, the laptop maker released security updates for 25 models, including ThinkPads, Yoga Slims and IdeaPads. Security vulnerabilities that undermine UEFI secure boot are serious because they allow attackers to install malicious firmware that survives operating system formats.
The Unified Extensible Firmware Interface, or UEFI, is the software that bridges a computer's firmware with its operating system. As the first piece of code that runs when a computer starts up, it is the first link in the security chain. Because UEFI resides on a flash chip on the motherboard, infections are very difficult to detect and remove.
Standard measures such as a hard disk format and reinstallation of the operating system do not help, because the infected UEFI will re-infect the computer when it starts.
ESET said that vulnerabilities CVE-2022-3430, CVE-2022-3431 and CVE-2022-3432 allow disabling UEFI Secure Boot or resetting the Secure Boot database (and dbx) to factory default settings. . Secure Boot uses databases to allow and deny mechanisms. The DBX database, in particular, stores encrypted hashes of denied keys.
Disabling or resetting databases to default values allows an attacker to override restrictions that would normally apply.