If you’ve followed the buzz around the web recently- without notifying the users Chrome made it tough to install Chrome extensions that are hosted elsewhere, user needs to drag and drop extension to Chrome extensions page to install the extension this raised some debate, Chrome team backs it self they done this on the security perspective of user to prevent malicious extensions install, now Opera to follow Chrome by whitelisting addons.Opera.com by default to allow install of extensions and users in coming days need to whitelist sites they want to install extensions from. Unlike to Chrome team, Opera here letting the users know about this before making these changes.
Opera to Make Install of Extensions From Third-Party Sites Bit Difficult to Avoid Malware
As usual Opera users can install extensions from Opera add-ons catalog without any problem, but they can’t install extensions hosted on other sites, even though they’re trusted.
Opera found some people trying use Opera ‘s extension framework to built malware, though Opera reviews the code of extension submitted to them and they only approves it if the extension follows their guidelines. They don’t have control on extensions hosted elsewhere and any user can easily click “ok” to security dialog shown by Opera on third-party site and puts him self into risk if that extension is malicious.
Instead of letting users know this change as surprise as happened for Chrome users, they’re announcing about this change much before and they’ll announce about these once they implement in Opera browser.
What we’re assuming is user need to whitelist third-party site by adding it under “Trusted Websites” in Security section under Advanced Tab.
Source: Opera Add-ons blog