I have dynamic parameters, so each time asm block the parameter. That's why I'm asking if i have unchecked this violation is it risky ?
note that all parameter value with meta characters will be blocked.
so how illegal parameters affect website security?
There is no 100% correct answer is it risky or not - it depends on application.
If you know all parameters, which are allowed in your app, then defining such list and forbid all other parameter will be a good protection.
The more strict configuration you define, the better protection you will get.
As I see, there are several ways how you can avoid block by "Illegal parameter" violation without disabling it:
This happens because you have special characters in name of wildcard parameter.
To make it work like special character you need to create wildcard parameter with name Terms\[*\].Groups