OpenSTAManager is an open source management software for technical assistance and invoicing. In 2.9.8 and earlier, a privilege escalation and authentication bypass vulnerability in OpenSTAManager allows any attacker to arbitrarily change a user's group (idgruppo) by directly calling modules/utenti/actions.php. This can promote an existing account (e.g. agent) into the Amministratori group as well as demote any user including existing administrators.

Affected: Packagist: devcode-it/openstamanager

### Summary A privilege escalation and authentication bypass vulnerability in OpenSTAManager allows any attacker to arbitrarily change a user's group (`idgruppo`) by directly calling `modules/utenti/actions.php`. This can promote an existing account (e.g. agent) into the Amministratori group as well as demote any user including existing administrators.

### Details `modules/utenti/actions.php` is reachable directly via `http://<IP>:8080/modules/utenti/actions.php` and processes privileged information without requiring any authentication or authorization checks on fields like idgruppo. As a result, an attacker can submit a crafted POST request that updates the targets record and assigns it to the administrator group.

The file explicitly sets: ```PHP $skip_permissions = true; include_once __DIR__.'/../../core.php'; ``` `core.php` then invokes:

```PHP Permissions::skip(); ``` Thus, disabling any authentication and permission enforcement. As a result, this file processes operations based on the `op` parameter in the POST request, not only `update_user`. Sensitive fields like `idgruppo` and others can be updated without verifying anything.

### PoC A target username exists, such as "agent" with an ID of 4. No authentication or cookies are required. Send the following POST request via Burp Suite or similar: <img width="1094" height="255" alt="image" src="https://github.com/user-attachments/assets/2e8cb148-1b5d-4e5c-9c73-05ed75d64188" /> The target's group is updated in the datab…