ET INFO Suspicious Domain (polyfill .io) in TLS SNI

Query · suricata

flow:established,to_server;
tls.sni; dotprefix;
content:".polyfill.io"; endswith; fast_pattern;
threshold:type limit, count 1, seconds 120, track by_src;
Raw source ET INFO Suspicious Domain (polyfill .io) in TLS SNI · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
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;
)

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