Bs_Def.sys
Default BIOS Flash Driver file version info
Driver on Windows LOLDrivers vulnerable driver 1 Sigma rule names it
A known vulnerable driver
T1068Exploitation for Privilege Escalation
From LOLDrivers (Apache 2.0). A driver is known by its hash: a sample under another name is the same driver. In Ceplin, "<sha256>".whatis() says which sample a hash is.
Is it the real Bs_Def.sys?
ProductSupport SST39SF020,SST29EE020,AT49F002T,AT29C020,AM29F002NT,AM29F002NB,V29C51002T,V29C51002B,M29F002T,W29C020., AsusTek Computer Inc.
DescriptionDefault BIOS Flash Driver
From the file’s version info, as recorded by xCyclopedia (MIT). A copy in another folder, signed by someone else or with another hash is not necessarily malicious, but it is worth a closer look.
What detects it
Sigma names Bs_Def.sys in 1 rule, for every kind of event; none is a process creation rule CmdID evaluates, so none is listed.