wininit.exe

wininit.exe is a core background process that runs early in the Windows startup sequence. After smss.exe creates session 0, the session reserved for system services, it launches wininit.exe to continue the initialization of that session. The smss.exe copy that starts it exits as soon as its work is done, so a real wininit.exe shows no parent in the process tree.

wininit.exe is responsible for starting several critical background processes that keep Windows running. Most notably, it launches services.exe (the Service Control Manager, which starts and manages Windows services), lsass.exe (the Local Security Authority process, which handles authentication and security policy), and historically lsm.exe (the Local Session Manager). Before Windows 10, lsm.exe was its own process started here. As of Windows 10 that role moved into a service DLL (lsm.dll) hosted by svchost.exe. It also sets up the temp folder and the rest of the session 0 environment. Once its startup duties are complete, it remains running quietly in the background until shutdown.

The genuine wininit.exe is a trusted, signed Microsoft system file that is essential to normal operation. Only one instance ever runs, as NT AUTHORITY\SYSTEM in session 0 from C:\Windows\System32\wininit.exe. It should never be removed or disabled, and terminating it will destabilize or crash the system, since the processes it manages are vital to Windows functioning.

Like other trusted system processes, wininit.exe is sometimes imitated by malware attempting to avoid detection (T1036.005). A legitimate copy always resides in C:\Windows\System32 and carries a valid Microsoft signature. Be suspicious of copies in other locations, slight misspellings such as wininitt.exe or wininit32.exe, and any instance that appears minutes or hours after boot, since the real one starts once, at startup.

wininit.exe also has a fixed position in the process tree. A legitimate instance has no parent, and its only children are services.exe and lsass.exe. An instance that was started by another running process, or that spawns anything beyond that pair, deserves a closer look, and a child like a command shell points to injected code or a spoofed parent (T1134.004). The relationship is worth checking from the other direction too: a process claiming to be lsass.exe whose parent isn't wininit.exe is a classic credential-theft anomaly.