alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET POLICY Vulnerable Java Version 21.0.x Detected"; flow:established,to_server; flowbits:set,ET.http.javaclient.vulnerable; http.user_agent; content:"Java/21.0."; fast_pattern; content:!"4"; within:1; threshold:type limit, count 2, seconds 300, track by_src; reference:url,www.oracle.com/java/technologies/javase/21u-relnotes.html; classtype:bad-unknown; sid:2049681; rev:4; metadata:affected_product Java, attack_target Client_Endpoint, created_at 2023_12_13, deployment Perimeter, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_07_18;)