Kangstools.com is an unsafe website dedicated to the propagation of a browser-based scheme. The goal pursued by Kangstools.com is to generate revenue for its creators by deceiving users into subscribing to its push notifications. Anyone who fails to notice the red flags will then start to suffer from various unwanted advertisements being generated on the screen of the device directly.
This tactic relies on social-engineering tricks to be successful. The most common case is making the unsafe websites present the users with supposed bot captcha checks and ask their visitors to click the 'Allow' button to prove they are, in fact, not robots. Kangstools.com, however, has chosen a different trick - it displays a black screen with a buffering icon with the message 'Click Allow to continue,' which will be placed underneath. All those who let their curiosity get the better of their sound judgment will fall into Kangstools.com's trap.
With Kangstools.com being granted all of the permissions it requires, it will proceed to generate various pop-up advertisements. Clicking on any of the advertisements could redirect the user to shade third-party websites that could be promoting other schemes. It is strongly recommended to deal with Kangstools.com as soon as you notice any suspicious signs.
What victims of this scheme have to do is not that complex. Just open the 'Settings' menu of the affected browser, scroll down to the 'Permissions' section, and remove all permissions granted to any sight that might be deemed as suspicious.