bs_rcio64.sys

bs_rcio64.sys is the 64-bit build of the BIOSTAR RACING GT Evo motherboard utility driver curated separately as bs_rcio.sys. Both ship as part of BIOSTAR's RACING GT Evo overclocking and system-tuning suite for the Racing-series boards. Family siblings already on the LOLDrivers list and in the Field Guide include bs_hwmio64_w10.sysDriverbs_hwmio64_w10.sysBIOSTAR hardware I/O driverOpen plate →, bs_i2cio.sysDriverbs_i2cio.sysBIOSTAR I2C interface driverOpen plate →, and bs_hwmio64.sys.

The access surface is the same as the 32-bit variant: low-level I/O and physical-memory access for hardware tuning, with insufficient access control on the device object so any local process can use the driver's kernel-level capabilities. CVE-2021-44852 covers the bs_rcio.sysDriverbs_rcio.sysBIOSTAR RACING GT Evo motherboard utility driverOpen plate → lineage broadly.

If you do not own a BIOSTAR Racing-series board, this file has no business being on disk. If you do, update the RACING GT Evo utility; Microsoft's Vulnerable Driver Blocklist blocks the older signed builds from loading.

bs_rcio64.sys is listed as a known-vulnerable driver on the public LOLDrivers project. One distinct binary hash matching this filename is on record.