Storage-based intrusion detection allows storage systems to transparently watch for suspicious activity. Storage systems are well-positioned to spot several common intruder actions, such as adding backdoors, inserting Trojan horses, and tampering with audit logs. Further, an intrusion detection system (IDS) embedded in a storage device continues to operate even after client systems are compromised. This paper describes a number of specific warning signs visible at the storage interface. It describes and evaluates a storage IDS, embedded in an NFS server, demonstrating both feasibility and efficiency of storage-based intrusion detection. In particular, both the performance overhead and memory required (40 KB for a reasonable set of rules) are minimal. With small extensions, storage IDSs can also be embedded in block-based storage devices. We thank the members and companies of the PDL Consortium (including EMC, Hewlett-Packard, Hitachi, IBM, Intel, Microsoft, Network Appliance, Panasas,...
Adam G. Pennington, John Linwood Griffin, John S.