Chinese computer manufacturer Lenovo has issued a security advisory to warn of several high-severity BIOS vulnerabilities impacting hundreds of devices in the various models (Desktop, All in One, IdeaCentre, Legion, ThinkCentre, ThinkPad, ThinkAgile, ThinkStation, ThinkSystem).
Exploiting the flaws may lead to information disclosure, privilege escalation, denial of service, and, under certain circumstances, arbitrary code execution.
The vulnerabilities in Lenovo’s security advisory are the following:
- CVE-2021-28216: Fixed pointer flaw in TianoCore EDK II BIOS (reference implementation of UEFI), allowing an attacker to elevate privileges and execute arbitrary code.
- CVE-2022-40134: Information leak flaw in the SMI Set Bios Password SMI Handler, allowing an attacker to read SMM memory.
- CVE-2022-40135: Information leak vulnerability in the Smart USB Protection SMI Handler, allowing an attacker to read SMM memory.
- CVE-2022-40136: Information leak flaw in SMI Handler used for configuring platform settings over WMI, enabling an attacker to read SMM memory.
- CVE-2022-40137: Buffer overflow in the WMI SMI Handler, enabling an attacker to execute arbitrary code.
- American Megatrends security enhancements (no CVEs).
SMM (Ring -2) is part of the UEFI firmware that provides system-wide functions like low-level hardware control and power management.
Access to SMM could be extended to the operating system and RAM, and storage resources; that’s why both AMD and Intel have developed SMM isolation mechanisms to keep user data safe from low-level threats.
