nis.exe is a program which is probably legit. So, if nis.exe is on your system, it is probably ok, and will NOT cause problems. Even if your system is virus-free, it is still recommended to use a good antivirus with a good detection rate, in order to yourself your system against viruses and malware.
Normally, this program is located in C:\Program Files (x86)\Norton Internet Security\Engine\18.104.22.168\nis.exe.
The MD5 fingerprint for this file is 9b8995e49134686a7d1a5b04845ca130.
This program is set up as a Windows service. This means it runs on your system in background, usually without displaying any user interface to you. Most Windows services are useful programs, which perform useful features to other programs or to Windows in general.
This application uses the Internet to communicate. Today this is ok. For example, most of the programs on your computer check for new updates. For this, Internet communications are necessary.
This is a x64 executable. It uses the full capacity of nowadays' CPUs.
The description extracted from the program is Norton Internet Security.
File version stored as a property 22.214.171.124.
Maker Symantec Corporation.
Legal copyright notice Copyright (c) 2017 Symantec Corporation. All rights reserved..
This application does NOT have visible windows. This is usually a bad thing.
nis.exe is digitally signed. Nowadays most legit software applications are digitally signed.
The digital signature found in nis.exe checks out perfectly. This is most likely a clean, ok program.
Digitally signed by: Symantec Corporation
Certificate's issuer name: VeriSign Class 3 Code Signing 2010 CA
It has an uninstall string in registry, which is a good sign. si are uninstall.