XProtect_AdLoad_B_1 was originally introduced as XProtect_AdLoad_B in version 2094. OSX/AdLoad is macOS Adware. Typical capabilities of Adware include the ability to install Potentially Unwanted Programs (PUPs), display/download unwanted advertising, change browser settings, and/or collect private user information [1].

References:

1. http://www.avgthreatlabs.com/en-ww/virus-and-malware-information/info/osx-adload