I changed the Chromium browser (as a masters project) to intercept suspicious extension actions like inserting elements etc and to alert users of what the extension is attempting to do. Using this proof-of-concept browser would have helped you debug your ad injection problem!
I once worked on a price comparison plugin and Firefox is very strict about what your plugins are allowed to do. They review each one and have some strict rules: like you can't load and execute Javascript from the web.
Most of our competitors just sent every URL you visited to their server. We wanted to be better than that since that is an obvious privacy issue.
So we made all our plugins (IE, FF, Chrome) download a whitelist (regex array) of shopping domains our search engine supported and it would only make API calls to our server if it matched that list AND you were on a product page.
Had the added benefit of reducing our server load too.
The server still gets a list of every page you visit on eCommerce sites but better than on all sites.
Not sure what the fuss is here, the permission is literally called "Read and change all your data on the websites that you visit". It should be obvious what it can do.
Seems like there should be some additional protection in the extensions API, if there is not already. "Read and change all your data on the websites that you visit" vs. "And send it somewhere over the web" are two separate layers of permission.
Footnote: I can't visit the page. Blocked by corporate.
Perhaps. I don't know browser internals well enough to know if they could backtrack all the various possible indirections. Hijacking already existing code, like Google analytics code on the page, for example (change the ga id).
If the extension has permission to manipulate webpages, then the extension could inject code (or an image element, etc) into any open webpage to make the webpage do the request for it.
Yes, this is the major issue. Authors also can sell their extension, then re-publish their own non-malwared version as an alternative, then just keep doing it over and over again.
I wrote some scripts to provide version pinning (just automates the manual editing of the manifests) but then you have to consider critical vulnerabilities in things like the LastPass extension where you absolutely want updates ASAP. So then you either have to have a curated extension list or maybe just separate extensions into "trusted" ie provided by reputable businesses as part of their product (lastpass, okta, etc) and "un-trusted." Even then, if the malware isn't in your face, you have no idea if the pinned version of your un-trusted extensions is actually non-malicious without auditing the code.
the fuss isn't so much that the permission is labeled wrong. its that the permission exists and theres no middle ground. I was trying to install an extension for pinboard a few weeks ago and it asked for the same thing. so of course i didn't install it. but its pretty lame you can't limit the scope.
My point exactly. Who would have thought that giving an extension permission to read and change all your data on website you visit would give the extension power to read and change all your data on website you visit.
Extensions (with permission to a domain) can inject elements and javascript into webpages, and javascript running in a page can use the DOM APIs (the same APIs that a webpage's own code uses) to see what's on the page, including form content.
Chrome extension sandboxing is mostly about controlling what webpages an extension can manipulate, not so much about how it can manipulate it. It's not obvious that there is a better sandboxing solution for the general case. (There are possibilities for specific uses though: Safari has APIs for extensions to use set up regexes to block images/ads without needing permission to run arbitrary code on sites.)
Read is not the same as send to external server. this is a big deal. it makes phishing incredibly easy and impossible to detect.
The ability of extensions to log form data to external servers allows for massive potential abuse. Not sure why Google would allow it. I imagine millions of logins have been stolen this way.
An adblocker is a good counter-example: it could work with an API that tracked the page changes and stopped e.g. JS or images inserted by the extension from loading. Even when editing the DOM, it has no need to load anything externally. Sounds possible, but I'm not sure how big the overhead of extending the DOM like that would be.
You probably could still create interactions with on-site JS that leak data sometimes, so it wouldn't be perfect, but that's page-specific and a lot more work.
I only heard about this a few week ago and I thought I was up-do-date on internet security. It may be obvious to others, I had no idea an extnetion could do this. This means it can steal you login like phishing but without a spoof URL. I now disable all extensions when logging into important websites
It's how SimilarWeb and other clickstream companies get their data. They claim it's harmless, but they have the ability to know everything you've inputted, and all the secure URL's you've visited (aka that intranet page with all your company salaries or passwords that you think nobody on the web knows about)
I never install browser extensions because it is difficult to check what they are doing and many of them require access to all sites. Users should check who wrote the extension and whether they trust the author.
https://cypher.codes/writing/intercepting-suspicious-chrome-...
- Note: my project specifically tries to protect users from Facebook hijacking and ad injection attacks - the two most common attacks on the CWS!