The detection rule titled 'GCP GKE Kubernetes Cron Job Created Or Modified' is designed to monitor the creation or modification of cron jobs within Google Kubernetes Engine (GKE). This rule recognizes that attackers might attempt to establish persistence within a GKE cluster by manipulating scheduled jobs. The rule is based on GCP Audit Logs, specifically monitoring for actions related to the creation and updating of Kubernetes cron jobs. It defines both creation and modification activities as critical events for detection. When such operations are detected, the system generates a notice with a severity level of 'Medium', prompting users to investigate potential unauthorized changes to cron jobs. The detection is triggered with a threshold of one occurrence and has a deduplication period of 60 minutes to minimize redundant alerts. The rule is linked to the MITRE ATT&CK framework under T1053.003, which corresponds to scheduled tasks. In case of detection, the recommended action is to investigate the rationale behind any cron job changes and to create a ticket if necessary, ensuring continued vigilance and security within the GKE environment.