Werk #13314: Distributed monitoring: Do not log site secret on remote site

This issue only affects you in case you are using a distributed monitoring setup and only affects the remote sites of a distributed setup.

When the central site is communicating with a remote site, this access from the central site to a remote system is authenticated used the so called site secret. This secret is handed over to the remote site with each remote call and validated.

Previous Checkmk versions were sending the site secret via GET parameters to the remote site. Which made the secret visible in the access log of the remote site apache (var/log/apache/access_log).

As these log files are normally only readable by the site user and the site secret is also known by the site user, this alone is not a information disclosure.

Of course it might happen that you forward a log, e.g. for error diagnosis, then this issue might be a real problem.

Therefore, we recommend all users to update to the next version to eliminate the problem for the future. Afterwards we recommend to check the log files (var/log/apache/access_log and var/log/apache/access_log.*.gz) and to remove problematic log entries. If your logs could be viewed by non Checkmk admins, you should also change the site secret.

If you change the site secret of a remote site, you will have to navigate to "Setup > Distributed monitoring", then "Logout" the remote site and "Login" the site again to make the central site know the new site secret.

CVSS:3.0/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L (https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L)

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