The Cisco Smart Install Oversized Packet Detection rule identifies oversized messages in the Cisco Smart Install (SMI) protocol by monitoring traffic to TCP port 4786. It utilizes the Network_Traffic data model to detect abnormally large payloads, which are indicative of potential exploits, such as those associated with CVE-2018-0171. The search query aggregates TCP traffic based on source and destination IP and collects statistics on packet counts and maximum byte sizes over hourly intervals. If the maximum byte size exceeds predefined thresholds, the rule alarms for possible vulnerabilities including remote code execution or denial-of-service attacks. Proper implementation requires tuning the search query and establishing a baseline for normal message sizes to minimize false positives from legitimate SMI operations, such as configuration transfers. If Smart Install is not necessary, disabling it is advised to enhance security. This rule is crucial for maintaining the integrity of Cisco devices exposed to Smart Install.