alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Suspicious Domain (polyfill .io) in TLS SNI"; flow:established,to_server; tls.sni; dotprefix; content:".polyfill.io"; endswith; fast_pattern; threshold:type limit, count 1, seconds 120, track by_src; reference:url,sansec.io/research/polyfill-supply-chain-attack; classtype:bad-unknown; sid:2053893; rev:1; metadata:affected_product Any, attack_target Client_and_Server, created_at 2024_06_26, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, updated_at 2024_06_26, reviewed_at 2024_10_04;)