Stylish can be used to customize and change the appearance of a webpage. After being sold by the original developer, Stylish has now fallen into the hands of SimilarWeb, which is malicious and dedicated to collecting user data, and will quietly collect browser records of Stylish users.
Stylish is an open source browser extension designed to modify the appearance of web pages by deploying custom stylesheets in addition to the Cascading Style Sheets (CSS) provided by websites themselves.
Heaton said Stylish, who was originally a Stylish extension, had been sold by its original developers in August 2016, changed hands several times and was later handed over to SimilarWeb, an analysis company notorious for collecting user data, in January 2016. Since Stylish, the app has been a spyware. It can record every website visited by 2 million users, and transmit these browsing behaviors to the remote server, with the unique identifier of the user. If the user has also established a Stylish account, it can easily create a link with the user identity.
Stylish has since disappeared from both the Firefox plugin page and the Chrome Web Store, after Heaton revealed the finding.
It’s not news, Heaton says, that browser extensions can be a security nightmare, and that once-trusted extensions can go aways when they quietly change owners. SimilarWeb’s claim that it must track the sites a user visits to recommend the best look for a page is a flimsy excuse. For this purpose, you only need to record the Domain of the current web page, not the full URL.
The default value on Stylish enables URL tracking and recording, but allows users to disable it. However, Heaton advised Stylish users to remove the extension and install a similar tool, such as the Stylus, an older Stylish branch. Article from: Huizhong Gao Science Center http://hertzhon.com.tw/