Gatekeeper
/usr/libexec/PlistBuddy -c "Print CFBundleShortVersionString" /private/var/db/gkopaque.bundle/Contents/Info.plist
XProtect
defaults read /Library/Apple/System/Library/CoreServices/XProtect.bundle/Contents/Info.plist CFBundleShortVersionString
MRT (Malware Removal Tool)
defaults read /Library/Apple/System/Library/CoreServices/MRT.app/Contents/Info.plist CFBundleShortVersionString