Well, just uninstall Flash player. No ad will remain, fortunately.
Download it again from the website for your region.
In China, Flash Player is exclusively distributed by 2144. The version of Flash Player distributed by 2144 is the only version of Flash Player licensed for use in China.
If you have feedback for 2144 on the software they bundle with Flash Player, or you need technical support with that version, please feel free to email firstname.lastname@example.org.
I'm in China for the next month and a half. I guess I have to put up with Malware until then or do without flash.
I guess Adobe does not find it poor practice that an American traveling to China has no choice but to have his flash overtaken by an automatic update that results in unreadable Chinese malware installation.
Pro-tip: if you originally installed the US version, the update should should not force a region/language change.