Vbulletin Security Token

@daydie

vBulletin uses a per-session anti-CSRF token that is emitted into the forum forms when you have an active session. The reliable way to get it for automated POSTs is to reproduce a browser login, preserve the session cookies, then fetch the actual post/reply form and read the hidden securitytoken field (this is the same pattern described by standard CSRF guidance) (OWASP CSRF).

Practical, minimal workflow:

• Perform the real login flow exactly as the forum does (GET the login page if it has hidden fields, POST credentials, follow redirects) while using an HTTP client that keeps a cookie jar.
• After successful login (verify by requesting your profile or a page that shows your username), GET the new-thread or reply page and parse the HTML for the hidden input named securitytoken. In a browser console you can read it with document.querySelector('input[name="securitytoken"]').value.
• Use the cookie jar plus that securitytoken value (and any other hidden form fields you find) when you POST the message. Include a reasonable Referer and User-Agent; follow redirects and keep cookies between requests.

Troubleshooting and cautions: if the token stays guest then the login did not persist — check that cookies are being saved and sent for the correct domain/path, that redirects are followed, and that there is no CAPTCHA or additional auth step. Tokens can expire and sites may add extra hidden fields, so always inspect the actual form HTML before posting. For complex sites, a headless browser (Puppeteer/Selenium) avoids many subtle cookie/JS issues. Also respect the forum Terms of Service and rate limits. For cookie mechanics see the MDN docs (Cookies).