HP on Wednesday announced the release of patches for two high-severity vulnerabilities that impact the UEFI firmware of more than 200 laptops, workstations, and other products.
The two vulnerabilities are tracked as CVE-2021-3808 and CVE-2021-3809 and have a CVSS score of 8.8. HP has credited Nicholas Starke of Aruba Threat Labs and a researcher who uses the online moniker “yngweijw” for reporting these bugs, but did not provide technical information on either of the flaws.
However, the company did share a list of impacted products, which includes numerous business notebooks and desktop PCs, as well as desktop workstations, retail point-of-sale devices, and thin client PCs.
“Potential security vulnerabilities have been identified in the BIOS (UEFI Firmware) for certain HP PC products, which might allow arbitrary code execution. HP is releasing firmware updates to mitigate these potential vulnerabilities,” HP notes in its advisory.
According to Starke, HP needed roughly six months to address CVE-2021-3809, the vulnerability he reported.
The security defect, he explains, is related to an SMI (System Management Interrupt) handler that calls out from System Management Mode (SMM), a highly privileged execution mode of x86 processors.
Starke claims that the SMI handler “can be triggered from a kernel execution context such as a Windows Kernel Driver,” which would allow an attacker to find the memory address of a specific function and overwrite it in physical memory so that it would point to attacker code.
“This vulnerability could allow an attacker executing with kernel-level privileges (CPL == 0) to escalate privileges to System Management Mode (SMM). Executing in SMM gives an attacker full privileges over the host to further carry out attacks,” Starke says.
While firmware updates are already available for most of the affected devices, a few of them have yet to receive patches. Users should read HP’s advisory for further details on impact and updates.
This week, HP also published advisories to detail patches that Intel has released to resolve multiple firmware and software vulnerabilities affecting its processors and chipsets, and which impact HP products as well.