I just found the message they sent me back then, here it is:
Hi James,
Sorry for the inconvenience brought to you.
The ads icon in quick access was meant for Chinese users. It was mistakenly pushed to international version of Maxthon.
It's not a virus, it is an advertisement for the 11th of November (11/11) festival, mainly celebrated in China as Singles' Day ( for people who are single). It has become the largest online shopping for Alibaba's sites Tmall and Taobao...
Do not worry, I'm talking to our team to see how this ad can be controlled and not be pushed to international users.
Maybe they have done it again?