Chip giant Intel has released an update to Basic Input Output Software (Bios) for its desktop and mobile motherboards.
Software running with kernel privileges can under certain circumstances change code running in System Management Mode, a privileged operating environment outside the control of the operating system, Intel warned in an advisory.
"Malicious software running in this environment could therefore perform any number of operations," Intel stated.
Motherboards affected by the flaw are DQ35JO, DQ35MP, DP35DP, DG33FB, DG33BU, DG33TL, DX38BT and MGM965TW, a mobile board.
The patch was released in response to the discovery and subsequent Black Hat 2008 presentation of a high-privilege rootkit for the Xen hypervisor by security researchers Joanna Rutkowska and Rafal Wojtczuk.