alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Lucy Security - Server Reply"; flow:established,to_client; http.server; bsize:4; content:"Lucy"; fast_pattern; http.header; header_lowercase; content:"cache-control|3a 20|no-store|2c 20|no-cache|2c 20|must-revalidate|2c 20|post-check|3d|0|2c 20|pre-check|3d|0|0d 0a|"; threshold:type limit, count 1, seconds 600, track by_src; classtype:bad-unknown; sid:2042970; rev:6; metadata:affected_product Web_Browsers, attack_target Client_Endpoint, created_at 2022_12_20, deployment Perimeter, deployment SSLDecrypt, malware_family Lucy, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_27;)