Git Config Error in Xcode
No, this isn't a virus1.

It seems that your name and email address are not set up properly in Git. Go to Xcode Preferences and then Accounts, select the repository, and check the username.

You can also do this via the command line:

git config --global user.email "you@example.com"
git config --global user.name "Your Name"


1: The message content can be found in /Library/Developer/CommandLineTools/usr/libexec/git-core/git (git version 2.7.4 (Apple Git-66) lines 11416-11424).