bsitf.sys

bsitf.sys and AsusBSItf.sys are ASUS BIOS Flash Driver naming variants distributed with the ASUS WinFlash utility. The 3.2.12.0 AsusBSItf.sys build exposes physical-memory reads through MmMapIoSpace (IOCTL 0x222804), contiguous kernel-memory allocation mapped to user mode through an MDL (IOCTL 0x222808), arbitrary I/O-port writes and reads (IOCTLs 0x222810 and 0x222818), and PCI configuration-space reads with BAR mapping (IOCTL 0x222814). Public research identifies this low-privilege interface as CVE-2024-33221 and demonstrates its use for privilege escalation, kernel code execution, or information disclosure. Earlier bsitf.sys builds tracked in this record additionally expose BIOS flash writes through IOCTL 0x22281C.

sc.exe create bsitf binPath=C:\windows\temp\bsitf.sys type=kernel && sc.exe start bsitf