Juju vulnerable to sensitive log retrieval via authenticated endpoint without authorization

Impact

Any user with a Juju account on a controller can read debug log messages from the /log endpoint.
No specific permissions are required - it's just sufficient for the user to exist in the controller user database.
The log messages may contain sensitive information.

Details

The /log endpoint is accessible at the following endpoints:
- wss://<controller-ip>/log
- wss://<controller-ip>/model/<model-uuid>/log

In order to connect to these endpoints, the client must pass an X-Juju-Client-Version header that matches the current version and pass credentials in a Basic Authorization header. Once connected, the service will stream log events even though the user is not authorised to view them.

To reproduce:

juju bootstrap
juju add-user testuser
juju change-user-password testuser

Run the wscat command below to
connect to wss://<controller-ip>:17070/api. Update the JSON payload to include the username and password that were created above.

wscat --no-check -c wss://contorller-ip:17070/model/modelUUID/api
{ "type": "Admin", "request": "Login", "version": 3, "params": { "client-
version": "3.6.1.0", "auth-tag": "user-testuser", "credentials": "
password" } }

Observe that the connection fails due to a lack of permissions.

Run the command below to connect to the log endpoint. Note that the credentials are passed in the --auth flag.

wscat --auth user-testuser:password -H "X-Juju-ClientVersion: 3.6.4" --no-check -c wss://<controller-ip>:17070/log

Observe that the logs are returned in the server’s response.

Code

The /log handlers are registered here
https://github.com/juju/juju/blob/3.6/apiserver/apiserver.go#L867
https://github.com/juju/juju/blob/3.6/apiserver/apiserver.go#L980

And the only auth required is that the incoming request be for an authenticated user

https://github.com/juju/juju/blob/3.6/apiserver/apiserver.go#L713

but no specific permission checks are done.

Workarounds

There are no workarounds.

References

F-01