ET INFO Possible Firefox Plugin install

Query · suricata

flow:to_server,established;
http.uri;
content:".xpi"; nocase; fast_pattern; endswith;
http.user_agent;
content:"|20|Firefox/";
Raw source ET INFO Possible Firefox Plugin install · Suricata
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Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET INFO Possible Firefox Plugin install";
    flow:to_server,established;
    http.uri;
    content:".xpi"; nocase; fast_pattern; endswith;
    http.user_agent;
    content:"|20|Firefox/";
    reference:url,research.zscaler.com/2012/09/how-to-install-silently-malicious.html;
    classtype:bad-unknown;
    sid:2016846; rev:6;
    metadata:created_at 2013_05_14, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_18;
)

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