Depends on the permissions requested by the extension but often yes. The permission "Can read all data on any webpage" means exactly that.
> Is there a way to use browser extensions safely?
Yes. Depending on your paranoia /security standards. Here's what you can do ( ordered by importance.)
1. Use more than one browser (but stay away from proprietary or less popular browsers) and/or use multiple profiles (both firefox and chrome has them)
2. Have separate profiles for banking, personal email, work and general browsing. (Also good for productivity)
3. Banking profile should have no extensions.
4. Use only mozilla-vetted 'recommended' and 'security reviewed' extensions in firefox for less important accounts. Check the permissions carefully and see if they're sane. I don't use extensions in chrome at all since google web store does no vetting at all beyond automated scanning. It's the wild west out there.
5. You can be less careful with general browsing profiles as long as you don't log into important accounts. Use firefox containers (this is more for privacy though than security)
6. If some addon is tempting but not reviewed - i try to review the code (if its small and readable enough). after vetting, i disable auto-updates. A greasemonkey script that does equivalent functionality is often preferable since the code is usually smaller and readable. Disable auto-update there too. Otherwise resist the temptation to install too many addons.
Of course it doesn't help that it's a finance site that disables paste for which I need an extension to reenable, but at least I'm not letting the rest of my extensions get at my banking web session.
This seems so dumb. Is this the best solution from google/mozilla/etc? I am thinking that an option to disable all extensions on a particular site/tab could solve many issues, maybe even with default on for well known email and bank providers. This would encourage ppl to install more extensions because they don't care what happens when they just read reddit.
For me, an extension can only require so much hands on effort before that effort outweighs the rewards of the extension. Years ago I had the Vimium plugin and loved it, but the provided functionality isn't worth the necessary audits. Not wanting to have to trust that it never sells out or gets hacked, I got rid of it. These days I just use a small handful of extensions (ublock origin, noscript, vuejs devtools) that I feel comfortable trusting and that make a significant impact on my browsing experience. I can manage without the rest.
- Firefox has 'recommended' addons. In addition some of the more popular addons are security vetted (Their addon pages doesn't come with the scary "not reviewed" warning. These can be reasonably assumed to be safe.
- Also read my other reply to gp.
> These days I just use a small handful of extensions
Same here. Resisting fomo and temptations for new shiny is the hardest part but still worthwhile imo
(You could also audit the extension for complete safety, but TBH I'm usually too lazy to do that, and I assume that the risk of an extension currently being malicious is far lower than the risk of an extension later being updated to become malicious)
It also insulates you from critical security updates. Managing your own security is not without its risks.