Opera has fixed a worrying security vulnerability, which could have allowed threat actors to access permissive APIs in the browser, and thus take over accounts, tweak browser settings, and even take screenshots.
Cybersecurity researchers GuardioLabs disclosed their findings, and dubbed the vulnerability “CrossBarking”.
The flaw revolves around the fact that multiple Opera-owned, publicly accessible subdomains, have privileged access to private APIs embedded within the browser. These domains support different features of the browser, such as the Pinboard, Opera Wallet, and others. By abusing browser extensions, crooks could inject malicious JavaScript into these domains, and thus gain access to the APIs.
Malicious extensions
“The content script does have access to the DOM (Document Object Model),” the researchers explained in a blog post. “This includes the ability to dynamically change it, specifically by adding new elements.”
Access to the APIs then allow crooks to screenshot open tabs, pull session cookies to access different accounts, and modify the browser’s DNS-over-HTTPS settings to resolve domains through malicious DNS servers. This, the researchers further explain, could lead to victims opening fake bank sites and losing banking credentials.
To demonstrate that the vulnerability works, GuardioLabs published a small browser extension to the Google Chrome Web Store. From there, an Opera browser user picks it up and compromises their device. The silver lining here is that the extension requires permission to run JavaScript on any web page, and particularly those that have access to private APIs.
Luckily, Opera has already addressed the issue and fixed the flaw in…
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