Let's try out the widget...
First it was Facebook, now Google has changed their Terms & Conditions to allow them to use your name, photo, and reviews in the ads they display. This is supposed to start on Nov 11, 2013, but you can opt out. Mostly.
You can opt out: https://plus.google.com/settings/endorsements?hl=en but that won't stop the practice of showing people in your network when you hit +1 for a site, which is not a new feature.
If you really don't want to show up anywhere, don't hit any +1s or leave reviews on Google products or in the Google Play store.
In short, they set up a free Dropbox account, uploaded the malware, and shared it publicly. If you'd like more info, check out: http://www.nbcnews.com/technology/dropbox-used-chinese-hackers-spread-malware-6C10642402