Description

Reflected Cross-Site Scripting attacks are also known as non-persistent attacks which occur when a malicious script is reflected back from a web application to the victim's browser. The script is activated through a link, which sends a request to the website with a vulnerability that enables the execution of malicious scripts.

Proof of concept: (POC)

1. After installing the Country Selector Plugin, go to the homepage of the WordPress site.

2. Capture all the requests and find the POST request to the AJAX call of check_country_selector.

Figure 01: Original AJAX Request

3. Enter the payload - <img+src=x+onerror=alert(document.cookie)> in the country parameter and <img+src=x+onerror=alert(document.cookie)> in the lang parameter.

Figure 02: Injected XSS Payloads in “country” and “lang” Parameter

4. Forward the request

5. Injected XSS payload will be reflected and triggered on the user’s browser.

Figure 03: Injected JavaScript Code for “lang” and “country” Parameters is Executed On The User’s Browser

Figure 04: The Default Cross-Site Scripting Mitigation Setting in wp.config file to Prevent XSS Attacks

Impact

An attacker can perform the following -

• Inject malicious code into the vulnerable variable and exploit the application through the Cross-Site Scripting vulnerability.

• Modify the code and get the session information of other users.

• Compromise the user machine.

Remediations

• Perform context-sensitive encoding of entrusted input before it is echoed back to a browser using an encoding library throughout the application.

• Implement input validation for special characters on all the variables that are reflected in the browser and stored in the database.

• Explicitly set the character set encoding for each page generated by the webserver.

• Encode dynamic output elements and filter specific characters in dynamic elements.

Timeline

March 24, 2022: Discovered in `WordPress Country Selector Plugin Version 1.6.5` Product

March 25, 2022: Reported to Welaunch

March 29, 2022: Acknowledged by Welaunch

March 30, 2022: Vendor Released Patch for XSS Vulnerability

March 31, 2022: CSW Assigned the CVE-2022-28290

Discovered by

Cyber Security Works Pvt. Ltd.