Splunk can be used to detect insider threats and fraud through monitoring and correlating machine data from various sources. It summarizes use cases where Splunk helped detect disgruntled employees stealing intellectual property, data leakage, and classroom fraud at an education company. It also discusses how Splunk detected millions of dollars in payment fraud at a cash wire transfer company by identifying emerging patterns. Finally, it provides examples of fraud patterns that could be detected at Etsy such as traffic from cloud services or brute force password attempts.