Lenovo laptop users should be especially careful. ESET has just announced that it has discovered three vulnerabilities (CVE-2021-3971, CVE-2021-3972, CVE-2021-3970) in the UEFI of Lenovo laptops.
The security holes have been marked as extremely critical. Exploits allow attackers to develop and execute malware in UEFI such as LoJax or ESPecter on all affected devices.
ESET published all the essentials on its blog. Security vulnerabilities affect various Lenovo laptop models.
CVE-2021-3971, CVE-2021-3972
The two first of these vulnerabilities – CVE-2021-3971, CVE-2021-3972 – affect UEFI firmware drivers.
Affected UEFI firmware drivers can be enabled by attackers to disable features protections SPI flash (BIOS control register bits and protected-range registers) or the ability to securely boot UEFI from a privileged user process during operating system runtime.
Exploiting these vulnerabilities allows intruders to successfully develop and execute SPI flash or ESP implants such as LoJax or UEFI ESPecter on affected devices.
CVE-2021-3970
While investigating the above security gaps, the third vulnerability was also discovered. May cause SMM memory corruption in SW SMI handler mode (CVE-2021-3970). The vulnerability allows arbitrary writes to and from SMRAM, which could lead to the execution of malicious code with SMM privileges and possibly using some SPI flash implant.
All vulnerabilities discovered were reported to Lenovo on October 11, 2021. Lenovo confirmed the vulnerabilities on November 17, 2021 and registered the CVEs.
The list of affected devices includes more than a hundred different laptop models with millions of users worldwide, from affordable models like the Ideapad-3 to more advanced models like the Legion 5 Pro-16ACH6 or the Yoga Slim 9-14ITL05.
The full list of affected models was published in Lenovo Advisory. Lenovo systems that have been manufactured since February 25, 2022, are not affected.
