To protect distributed network resources and assets, collaborative intrusion detection systems/networks (CIDSs/CIDNs) have been widely deployed in various organizations with the purpose of detecting any potential threats. While such systems and networks are usually vulnerable to insider attacks, some kinds of trust mechanisms should be integrated in a real-world application. Challenge-based trust mechanisms are one promising solution, which can measure the trustworthiness of a node by sending challenges to other nodes. In the literature, challenge-based CIDNs have proven to be robust against common insider attacks, but it may still be susceptible to advanced insider attacks. How to further improve the robustness of challenge-based CIDNs remains an issue. Motivated by the recently rapid development of blockchains, in this work, we aim to combine these two and provide a blockchained challenge-based CIDN framework. Our evaluation shows that blockchain technology has the potential to enhance the robustness of challenge-based CIDNs in the aspects of trust management (i.e., enhancing the detection of insider nodes) and alarm aggregation (i.e., identifying untruthful inputs).