alert tcp any any -> any any (msg:"ET POLICY ZIPPED XLS in transit"; flow:established; content:"|50 4B 03 04|"; content:"|00|"; content:".xls"; nocase; classtype:not-suspicious; sid:2001403; rev:5; metadata:created_at 2010_07_30, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)