The rule titled "Network Sniffing via Tcpdump" identifies the execution of the Tcpdump program on Linux hosts, which is commonly used for network monitoring and packet sniffing. Tcpdump can be a tool for attackers to capture sensitive credentials or data in transit, serving as an initial step towards lateral movement or evasion of defenses. The detection is based on monitoring process creation events where the Tcpdump process is initiated. It's crucial to understand that while Tcpdump has legitimate uses by network administrators for troubleshooting, its invocation can signify malicious activity if linked with other suspicious behaviors. The rule utilizes data from auditbeat and endpoint logs to trigger alerts when Tcpdump is run, aiding in the identification of potential credential access or reconnaissance efforts by threats.