Troj/Multidr-AC drops Troj/Startpa-BZ as <Windows>\szchost.exe.
The Trojan also sets the following registry entry to autorun the dropped Trojan on system startup:
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\
Zone system = "C:\WINDOWS\szchost.exe"
Troj/Multidr-AC then executes the dropped Trojan.