Troj/Zbot-A is a Trojan for the Windows platform.
When Troj/Zbot-A is installed it creates the file <System>\ntos.exe.
The following registry entry is changed to run ntos.exe on startup:
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Userinit
<System>\userinit.exe,<System>\ntos.exe,