If IT systems in an information domain no longer provide the required log data, it will no longer be possible to appropriately detect security incidents. Errors in hardware and software and incorrectly administered IT systems can be the cause of such data source failures. In particular, if the failure of data sources is not detected, this may result in a false perception of an organisation's security situation. Attackers may thus remain undetected for a long period of time and be able to intercept organisation-critical information or manipulate production systems (for example).