A critical vulnerability has been discovered in the browser app comes pre-installed on hundreds of millions of Samsung Android devices that could allow an attacker to steal data from browser tabs if the user visits an attacker-controlled site.

Identified as CVE-2017-17692, the vulnerability is Same Origin Policy (SOP) bypass issue that resides in the popular Samsung Internet Browser version 5.4.02.3 and earlier.

The Same Origin Policy or SOP is a security feature applied in modern browsers that is designed to make it possible for web pages from the same website to interact while preventing unrelated sites from interfering with each other.

In other words, the SOP makes sure that the JavaScript code from one origin should not be able to access the properties of a website on another origin.
The SOP bypass vulnerability in the Samsung Internet Browser, discovered by Dhiraj Mishra, could allow a malicious website to steal data, such as passwords or cookies, from the sites opened by the victim in different tabs.

"When the Samsung Internet browser opens a new tab in a given domain (say, google.com) through a Javascript action, that Javascript can come in after the fact and rewrite the contents of that page with whatever it wants," researchers from security firm Rapid7 explained.

"This is a no-no in browser design since it means that Javascript can violate the Same-Origin Policy, and can direct Javascript actions from one site (controlled by the attacker) to act in the context of another site (the one the attacker is interested in). Essentially, the attacker can insert custom Javascript into any domain, provided the victim user visits the attacker-controlled web page first."

Attackers can even snag a copy of your session cookie or hijack your session and read and write webmail on your behalf.

Mishra reported the vulnerability to Samsung, and the company replied that "the patch is already preloaded in our upcoming model Galaxy Note 8, and the application will be updated via Apps store update in October."

Meanwhile, Mishra, with the help of Tod Beardsley and Jeffrey Martin from Rapid7 team, also released an exploit for Metasploit Framework.

Rapid7 researchers have also published a video demonstrating the attack.

Since the Metasploit exploit code for the SOP bypass vulnerability in the Samsung Internet Browser is now publicly available, anyone with less technical knowledge can use and exploit the flaw on a large number of Samsung devices, most of which are still using the old Android Stock browser.