ET MALWARE Suspected REDCURL CnC Activity M2

Query · suricata

flow:established,to_server;
http.method;
content:"HEAD";
http.uri;
content:".jpg"; endswith;
http.user_agent;
content:"curl/"; startswith; fast_pattern;
http.header_names;
content:"|0d 0a|Host|0d 0a|User-Agent|0d 0a|Accept|0d 0a 0d 0a|"; bsize:30;
content:!"Referer";
Raw source ET MALWARE Suspected REDCURL CnC Activity M2 · 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 MALWARE Suspected REDCURL CnC Activity M2";
    flow:established,to_server;
    http.method;
    content:"HEAD";
    http.uri;
    content:".jpg"; endswith;
    http.user_agent;
    content:"curl/"; startswith; fast_pattern;
    http.header_names;
    content:"|0d 0a|Host|0d 0a|User-Agent|0d 0a|Accept|0d 0a 0d 0a|"; bsize:30;
    content:!"Referer";
    reference:url,www.group-ib.com/resources/threat-research/red-curl.html;
    reference:md5,12ec7e6876dc86f158f448ebfba9e0eb;
    classtype:command-and-control;
    sid:2030689; rev:2;
    metadata:attack_target Client_Endpoint, created_at 2020_08_17, deployment Perimeter, deployment SSLDecrypt, performance_impact Moderate, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_17;
)

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