Sweet Captcha Injects Popup Ads
 

For those who use sweetCAPTCHA on blogs, for example, they are injecting malicious popups.

• June 8, 2015 Sweet Captcha Injects Popup Ads
• June 9, 2015 pop-under ads come with the plugin
• June 9, 2015 Injects Spam with Malicious Code
• June 9, 2015 sweetCAPTCHA Injecting Pop Up Ads on Purpose
• June 9, 2015 sweetCAPTCHA hacked and causing malicious popups

If you use sweetCAPTCHA, you might want to remove it.