This is a Windows system installed file with Windows File Protection (WFP) enabled.
There are 66 versions of wuaueng.dll in the wild, the latest version being 7.9.9600.17093 (winblue_gdr.140410-1503). The average file size is about 1.19 MB. The file is a digitally signed and issued to Microsoft Corporation by Microsoft Corporation. The executable is a .NET framework assembly utilizing the CLR.
If Windows Update or Automatic Updates is turned on, the latest version of the Windows Update Agent will be automatically downloaded and installed on your computer. If you go to Windows Update before it gets installed automatically, you will see a message to install the Windows Update Agent.
(Note, the behaviors below are for all versions of wuaueng.dll, select a unique version for details.)
United States installs about 51.19% of Windows Update Agent.