Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. Starting in version 0.7.0 and prior to versions 0.7.15 and 0.8.3, Himmelblau is vulnerable to leaking credentials in debug logs. When debug logging is enabled, user access tokens are inadvertently logged, potentially exposing sensitive authentication data. Similarly, Kerberos Ticket-Granting Tickets (TGTs) are logged when debug logging is enabled. Both issues pose a risk of exposing sensitive credentials, particularly in environments where debug logging is enabled. Himmelblau versions 0.7.15 and 0.8.3 contain a patch that fixes both issues. Some workarounds are available for users who are unable to upgrade. For the logon compliance script issue, disable the logon_script option in /etc/himmelblau/himmelblau.conf, and avoid using the -d flag when starting the himmelblaud daemon. For the Kerberos CCache issue, one may disable debug logging globally by setting the debug option in /etc/himmelblau/himmelblau.conf to false and avoiding the -d parameter when starting himmelblaud.
Information written to log files can be of a sensitive nature and give valuable guidance to an attacker or expose sensitive user information.
While logging all information may be helpful during development stages, it is important that logging levels be set appropriately before a product ships so that sensitive user data and system information are not accidentally exposed to potential attackers. Different log files may be produced and stored for: