This detection rule, "Proofpoint Multiple Threats Detected," is designed to identify instances of emails that contain multiple active threats, serving as a red flag for sophisticated phishing attempts and malware attacks. The rule categorizes severity based on the number of identified threats: CRITICAL for five or more threats, HIGH for three to four threats, and MEDIUM for two threats. The rule operates by analyzing the logs generated by the Proofpoint email security platform, specifically looking for indicators of active threats such as malicious attachments, phishing URLs, and varying threat classifications. Upon detection, a structured response is triggered, which includes verifying and quarantining the email, blocking the sender's infrastructure, and escalating to the threat intelligence team for further investigation. The rule leverages the MITRE ATT&CK framework, specifically targeting techniques related to phishing (TA0001:T1566) and user execution (TA0002:T1204). Through robust testing scenarios, the rule has been validated for its efficacy in detecting both single and multiple threat instances, ensuring resilience against multi-vector attacks in email communications.