In what's a new phishing technique, it has been demonstrated that the Application Mode feature in Chromium-based web browsers can be abused to create "realistic desktop phishing applications."
Application Mode is designed to offer native-like experiences in a manner that causes the website to be launched in a separate browser window, while also displaying the website's favicon and hiding the address bar.
According to security researcher mr.d0x – who also devised the browser-in-the-browser (BitB) attack method earlier this year – a bad actor can leverage this behavior to resort to some HTML/CSS trickery and display a fake address bar on top of the window and fool users into giving up their credentials on rogue login forms.
"Although this technique is meant more towards internal phishing, you can technically still use it in an external phishing scenario," mr.d0x said. "You can deliver these fake applications independently as files."
This is achieved by setting up a phishing page with a fake address bar at the top, and configuring the --app parameter to point to the phishing site hosting the page.
It's worth noting that the mechanism works on other operating systems, such as macOS and Linux, making it a potential cross-platform threat. However, the success of the attack is predicated on the fact that the attacker already has access to the target's machine.
That said, Google is phasing out support for Chrome apps in favor of Progressive Web Apps (PWAs) and web-standard technologies, and the feature is expected to be fully discontinued in Chrome 109 or later on Windows, macOS, and Linux.
In a statement shared with The Hacker News, the internet giant said that "the --app feature was deprecated before this research was published, and we are taking its potential for abuse into account as we consider its future."
"Users should be aware that running any file provided by an attacker is dangerous. Google's Safe Browsing helps protect against unsafe files and websites. While Safe Browsing is enabled by default in Chrome, users may want to enable Enhanced protection, which inspects the safety of your downloads to better warn you when a file may be dangerous."
The findings come as new findings from Trustwave SpiderLabs show that HTML smuggling attacks are a common occurrence, with .HTML (11.39%) and .HTM (2.7%) files accounting for the second most spammed file attachment type after .JPG images (25.29%).