There are about 44 banks in Kenya, each with it different kind of websites  i presume.  So there's no straight answer to that question.  There's however a chrome web  browser extension,  built by, that can help you get the specific platform for each bank's website.
With respect to security, there are must have  security for almost all websites which again depends on lot other factors such as platform,  servers etc.  The specifics depends on the service that the banks wishes to offer through their website.