I've developed a few browser extensions, and every week I receive numerous emails with "revenue offer". Some experienced developers know that offers like these will inject malware into the browsers of your users, but scammers who make these offers will not tell you about it. They offer "integrations" that don't look so suspicious. Imagine how many developers have accepted these offers. Then look at the number of extensions in your browser and think about how much risk there is that you have an extension with malware.
Is it possible to decompile or analyze an extension to see if new code has been added?
I only have 4 extensions, all of them are recommended by Firefox, and come with a tag that says “Firefox only recommends extensions that meet our standards for security and performance”. Now I’m wondering what those standards are; and whether plugins that have already ‘met’ them, are re-assessed when updated or altered.
You can see the code of extensions, but it may be minimized, so it hard to known what the code do.
Extensions with label “Recommended” are pass the manual review of Firefox moderators, so you can trust them more than addons with no this label. However you still should keep in mind that any extension developer may be victim of complex scam attack.
The most probable reason usually is a not enough funding the developers
To minimize the possibility of hijacking addons by scammers, we have to:
From what I’ve experienced with my extension, every update has to go through a review process. Firefox is pretty fast, chrome takes a few days and edge takes a while (opera hasn’t finished reviewing my first version, so I stopped trying with them).
The only time I failed a review was early on when my build script choked and I submitted an empty file to Chrome (whoops). So I can’t really tell how good those reviews are, but I’m not planning on testing them.
You can open/extract extensions (at least Firefox ones) as zip files, they’ll contain the code and assets used by the extension.
They average person won’t know what they’re looking at.