Important: #92836 - Introduce sudo mode for Install Tool accessed via backend

See forge#92836


When accessing the Install Tool via backend user interface, currently logged in backend users have to confirm their user password again in order to get access to the Install Tool. As an alternative, it is also possible to use the install tool password (reasons described below in "side effects" section). This is done in order to mitigate unintended modifications that might occur as result of e.g. possible cross-site scripting vulnerabilities in the system.

Standalone Install Tool is not affected by sudo mode confirmation. This change enforces mitigation as mentioned in TYPO3-CORE-SA-2020-006.

Potential side effects

Albeit default local authentication mechanisms are working well, there are side effects for 3rd party extensions that make use of these auth service chains as well - such as multi-factor authentication or single sign-on handling.

As an alternative, it is possible to confirm actions using the Install Tool password, instead of confirming with users' password (which might be handled with separate remote services).

Services that extend authentication with custom additional factors (2FA/MFA) are advised to intercept only valid login requests instead of all authUser invocations.

class MyAuthenticationService
extends \TYPO3\CMS\Core\Authentication\AbstractAuthenticationService
    public function authUser(array $user)
        // only handle actual login requests
        if (empty($this->login['status'])
            || $this->login['status'] !== 'login') {
            // skip this service, hand over to next in chain
            return 100;
        // usual processing for valid login requests

Please see this pull-request for a 2FA/MFA extension as an example.