FUXA's scheduler API missing admin check enables operator-to-admin escalation via scheduled device actions
Summary
An authorization issue in the Scheduler API allowed authenticated non-admin users to create or modify scheduled actions that should be restricted to administrators.
Details
The Scheduler API did not correctly enforce administrator permissions when processing scheduler modifications.
As a result, authenticated users with non-administrative roles could create or modify scheduled actions that execute privileged operations, including device value changes and server-side script execution.
The issue was fixed in version 1.3.2 by enforcing the appropriate permission checks for scheduler modifications.
Impact
An operator-level user in FUXA reaches the PLC-write and server-side-script-execution surface that the platform otherwise restricts to administrators. In a SCADA deployment those two privileges cover setpoint control and the automation scripting engine. Alice schedules a job that rewrites a pump's enable tag, opens a safety interlock, or runs a project script that walks the device tree. The scheduled-action model extends the attack: Alice does not need to keep a session open for the action to fire, and a repeating schedule re-applies her changes every cycle even if an admin reverts them manually.
CVSS 3.1: AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L (Medium, 6.3). CWE-862.
Recommended Fix
Add authJwt.haveAdminPermission(permission) to both POST /api/scheduler and DELETE /api/scheduler, matching every other write endpoint that reaches runtime.devices.setTagValue or runtime.scriptsMgr.runScript.
schedulerApp.post("/api/scheduler", secureFnc, function(req, res) {
if (res.statusCode === 403) {
runtime.logger.error("api post scheduler: Tocken Expired");
return;
}
const permission = checkGroupsFnc(req);
const isGuest = authJwt.isGuestUser(req.userId, req.userGroups);
if (runtime.settings?.secureEnabled && (isGuest || !authJwt.haveAdminPermission(permission))) {
res.status(401).json({error:"unauthorized_error", message: "Unauthorized!"});
runtime.logger.error("api post scheduler: admin permission required");
return;
}
// ... rest unchanged ...
});Apply the same change to the delete handler at server/api/scheduler/index.js:102-112. As defense in depth, the scheduler service should also validate each deviceActions entry against the creator's stored groups before execution (e.g., reject onRunScript on any scheduler whose author is not an admin at execution time).
A fix is available at https://github.com/frangoteam/FUXA/releases/tag/v1.3.2.
*Found by aisafe.io*