TheHive
Scalable, open source and free security incident response platform
... and react to attacks you've dealt with. Additionally, when TheHive is used in conjunction with Cortex, security analysts and researchers can easily analyze tens if not hundreds of observables. Multiple analysts from one organization can work together on the same case simultaneously. For example, an analyst may deal with malware analysis while another may work on tracking C2 beaconing activity on proxy logs as soon as IOCs have been added by their coworker.