ET HUNTING Suspicious HTTP Server Value in Response (Apache \r\n)

Query · suricata

flow:established,to_client;
http.header;
content:"Server|3a 20|Apache|20 5c|r|5c|n|0d 0a|"; fast_pattern;
threshold:type limit,seconds 300,count 1,track by_src;
Raw source ET HUNTING Suspicious HTTP Server Value in Response (Apache \r\n) · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET HUNTING Suspicious HTTP Server Value in Response (Apache \r\n)";
    flow:established,to_client;
    http.header;
    content:"Server|3a 20|Apache|20 5c|r|5c|n|0d 0a|"; fast_pattern;
    threshold:type limit,seconds 300,count 1,track by_src;
    reference:url,blog.fox-it.com/2023/11/15/the-spelling-police-searching-for-malicious-http-servers-by-identifying-typos-in-http-responses;
    classtype:misc-activity;
    sid:2049205; rev:1;
    metadata:attack_target Client_Endpoint, created_at 2023_11_15, deployment Perimeter, deployment SSLDecrypt, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_11_15;
)

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