Security Experts:

Connect with us

Hi, what are you looking for?

SecurityWeekSecurityWeek

Vulnerabilities

Facebook Awards Researcher $20,000 for Account Hijacking Vulnerability

Security researcher Vinoth Kumar says Facebook awarded him $20,000 after he discovered and reported a Document Object Model-based cross-site scripting (DOM XSS) vulnerability that could have been exploited to hijack accounts.

Security researcher Vinoth Kumar says Facebook awarded him $20,000 after he discovered and reported a Document Object Model-based cross-site scripting (DOM XSS) vulnerability that could have been exploited to hijack accounts.

The researcher says he discovered the vulnerability in the window.postMessage() method, which is meant to safely enable cross-origin communication between Window objects.

The process of identifying the vulnerability, the researcher says, began with the Facebook Login SDK for JavaScript, which creates a proxy iframe v6.0/plugins/login_button.php for cross-domain communication.

What Kumar discovered was that the login SDK sends an initial payload to the proxy iframe, and that the payload contains the click URL of the ‘Continue with Facebook’ button, which is rendered in the proxy iframe.

When the user clicks the ‘Continue with Facebook’ button, the URL from the postMessage  payload is executed in the proxy iframe, which leads to JavaScript being executed on Facebook.com.

The researcher identified two manners in which the vulnerability could be exploited, one involving opening a pop-up window and then communicating with it, and the other relying on opening an iframe and communicating with it.

Successful exploitation of the vulnerability would have allowed an attacker to obtain the victim’s session cookies and hijack their account.

“Due to an incorrect post message configuration, someone visiting an attacker-controlled website and clicks login with the Facebook button would trigger XSS on facebook.com domain behalf of logged-in user. This would have let to 1-click account takeover,” Kumar explains.

He has published a video to demonstrate the attack:

Facebook was informed about the discovery on April 17. The social media platform addressed the vulnerability three days later by “adding facebook.com regex domain and schema check in the payload url param.” The company awarded the researcher a $20,000 bug bounty two weeks later.

Related: Facebook Paid $2.2 Million in Bug Bounty Rewards in 2019

Related: Facebook Rushes to Patch Bug Exposing Page Admins

Related: CSRF Vulnerability in Facebook Earns Researcher $25,000

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Expert Insights

Related Content

Mobile & Wireless

Technical details published for an Arm Mali GPU flaw leading to arbitrary kernel code execution and root on Pixel 6.

Mobile & Wireless

Apple rolled out iOS 16.3 and macOS Ventura 13.2 to cover serious security vulnerabilities.

Cloud Security

VMware vRealize Log Insight vulnerability allows an unauthenticated attacker to take full control of a target system.

Mobile & Wireless

Apple’s iOS 12.5.7 update patches CVE-2022-42856, an actively exploited vulnerability, in old iPhones and iPads.

Mobile & Wireless

Two vulnerabilities in Samsung’s Galaxy Store that could be exploited to install applications or execute JavaScript code by launching a web page.

Vulnerabilities

Security researchers have observed an uptick in attacks targeting CVE-2021-35394, an RCE vulnerability in Realtek Jungle SDK.

Vulnerabilities

Several vulnerabilities have been patched in OpenText’s enterprise content management (ECM) product.

Vulnerabilities

Google has awarded more than $25,000 to the researchers who reported the vulnerabilities patched with the release of the latest Chrome update.