iua.exe is part of MAS Users Application or Virus.VBInject.
If you installed Nortel Media Application Server on your computer, this file is safe. The Media Application Server (MAS) application is a generic media processing platform designed to use commercial hardware platforms and common operating systems without the presence of hardware-based DSP resources. The system exploits the advantages of multimedia protocols and the IP environment to achieve respectable performance comparable to more expensive DSP-based TDM solutions. The software-only approach to media processing is the natural evolution of existing TDM centric voice processing platforms as multimedia and data networks continue to converge.
If you didn’t install Nortel Media Application Server on your computer, this file is high risky. It could be part of virus named “VBInject”. Run Microsoft defender security center and scan your system immediately.
