Safe to run unsupported OS with up to date browser?

[moose232]

If a basic user that only uses a web browser for typical tasks, such as shopping, online banking etc. is running an unsupported OS eg. El Capitan, from a security-perspective (ignoring the general lack of application compatibility), is it enough to run an up to date version of a web browser (eg. Chrome/Firefox) and not worry about getting any security updates for the operating system?

 

Any and all articles around lack of os support/security patches are too basic in nature - i.e. no patches/support = BAD!!

 

Ideally, I'd like anyone with a deep understanding of why it's bad to explain in greater detail please. Apologies if this has already been answered elsewhere.

[moose232]

Anyone?!

[goretsky Supervisor]

Hello,

My concern would be accessing something that either escapes the browser's own sandboxing into the unsupported operating system, or downloading something via the web browser that exploits a vulnerability that will never be patched in the operating system.

Here's a blog post I wrote a few years ago about the problems of using out-of-date operating systems:  The Last Windows XP Security White Paper

 

That blog post, and it's accompanying 48-page paper, are about Windows XP and not macOS, but a lot of the hardening concepts are the same, as are the security concerns.

Regards,

Aryeh Goretsky