alert smtp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET SCAN StarDotStar HELO, suspected AUTH LOGIN botnet"; flow:established,to_server; content:"HELO|20 2a 2e 2a 0d 0a|"; depth:11; classtype:bad-unknown; sid:2026463; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_10_09, deployment Perimeter, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)