Identification of Tabnabbing

Tabnabbing is a type of phishing attack where a background tab changes its content and URL to impersonate a legitimate website, usually aiming to steal user information. This attack exploits the user's trust in previously opened tabs in their browser. When the user returns to the altered tab, they may believe they are still on the original site and enter sensitive information, which is then captured by the attacker.

Common Indicators of Tabnabbing:

  1. Unexpected Change in Web Content: A tab's content changes to a different site, especially a login page, while the user is not actively viewing it.
  2. Altered URLs: The URL in the address bar changes to a different domain or webpage without user interaction.
  3. Use of JavaScript: The attack typically uses JavaScript to detect when a tab is not active and then changes the content and URL.

How to Identify Tabnabbing:

  1. Manual Testing: Leave a website open in a tab, navigate to another tab, and then return to see if the content or URL changes unexpectedly.
  2. Code Review: Look for JavaScript code that listens for events indicating the user has switched tabs and code that dynamically changes the document's location or content.
  3. Automated Scanning Tools: While more challenging to detect with automated tools, some advanced security scanners might identify JavaScript behaviors that are indicative of tabnabbing.
  4. Security Audits: Regular security reviews of your website's code can help identify potential tabnabbing vectors, especially in the case of third-party script integrations.

Mitigation Strategies:

  1. Content Security Policy (CSP): Implement a Content Security Policy to control the resources that can be loaded and executed by the browser, reducing the risk of malicious JavaScript execution.
  2. External Link Handling: Add rel="noopener noreferrer" to anchor tags when linking to external sites. This prevents the new page from accessing the original page's window object.
  3. User Awareness: Educate users about the risks of tabnabbing and encourage them to manually type the URL of sensitive websites, like banking sites, rather than accessing them through a previously opened tab.
  4. Regular Monitoring: Regularly monitor and review your site for unexpected changes in behavior, especially after updates or the addition of new scripts.
  5. Use of Trusted Scripts: Ensure that only trusted and verified scripts are included on your website, reducing the risk of introducing tabnabbing through third-party code.

By understanding and implementing measures against tabnabbing, developers and website owners can protect users from this deceptive and potentially harmful attack.