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The ongoing convergence of Industrial Control Systems (ICSs) with the Internet introduces many challenges from security perspective. Particularly, the smart energy grid as large ICS and critical infrastructure, requires especial protection as the consequences of its failure can be severe. However, even a careful system design cannot prevent all attacks in advance. For this reason, the smart grid requires an additional line of defence that can be provided by a Collaborative Intrusion Detection System (CIDS) to detect unknown and ongoing attacks. In this paper, we describe the requirements to a CIDS for deployment in the smart grid. Furthermore, we discuss the design choices for such a system and summarize the arising challenges in the deployment of CIDSs in smart grids as well as present initial ideas to address them.

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Today's growing number of security threats to computers and networks also increase the importance of log inspections to support the detection of possible breaches. The investigation and assessment of security incidents becomes more and more a daily business. Further, the manual log analysis is essentially in the context of developing signatures for intrusion detection systems (IDS), which allow for an automated defense against security attacks or incidents. But the analysis of log data in the context of forensic investigations and IDS signature development is a tedious and time-consuming task, due to the large amount of textual data. Moreover, this task requires a skilled knowledge to differentiate between the important and the non-relevant information. In this paper, we propose an approach for log resp. audit data representation, which aims at simplifying the analysis process for the security officer. For this purpose audit data and existing relations between audit events are represented graphically in a threedimensional space. We describe a general approach for analyzing and exploring audit or log data in the context of this presentation paradigm. Further, we introduce our tool, which implements this approach and demonstrate the strengths and benefits of this presentation and exploration form. I. MOTIVATIONThe growing dependencies of social processes on IT infrastructures as well as their increasing complexity provide a large potential of threats that jeopardizes these processes. Furthermore, the number of security incidents has increased dramatically and continues to ascend annually [3], [4]. Consequently, the investigation and assessment of security incidents becomes more and more a daily business. Therefore, regularly security officers have to reconstruct and extract the actions of the attacker from system logs, which record the entire system behavior. System logs or audit trails record all security relevant actions of a system, whereby each action is described by an audit event. The investigation of these audit trails is extremely time-consuming and error-prone due to the flood of logged data and can be seen as "looking for the needle in the haystack". In addition to these investigations and the assessment of security incidents, an efficient digital forensic is also a crucial precondition for the development process of signatures for intrusion detection systems (IDS). In contrast to typical preventive security measures of IT systems (e.g. firewalls or virus-scanners), IDS allow for a reactive protection of systems. IDS provide means to detect occurred security violations automatically and to trigger appropriate countermeasures. Two complementary approaches are applied by IDS: anomaly and misuse detection. Anomaly detection aims at detecting abnormal user behavior and requires a comprehensive set of data describing the normal user behavior. Often it is difficult to provide these descriptions. That's why anomaly detection currently has only a limited importance in practice. Misuse detection focuses on the det...

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